I need help with this code in C#

This is an injector code for C# but i keep getting errors on [DllImport("kernel32.dll", SetLastError = true)]
can some one try to tell me whats wrong?Here's the code.and i did not make this credits go to wiccaan.

here's the static dll injector class code

Code:

---

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

//This is used to actually inject the specific DLL into the selected process

namespace InjectMe
{
    public static class Inject
    {
        private static class WINAPI
        {
            [DllImport("kernel32.dll", SetLastError = true)]
            public static extern IntPtr OpenProcess(
                UInt32 dwDesiredAccess,
                Int32 bInheritHandle,
                UInt32 dwProcessId);

            [DllImport("kernel32.dll", SetLastError = true)]
            public static extern Int32 CloseHandle(
                IntPtr hObject);

            [DllImport("kernel32.dll", SetLastError = true)]
            public static extern IntPtr GetProcAddress(
                IntPtr hModule,
                string lpProcName);

            [DllImport("kernel32.dll", SetLastError = true)]
            public static extern IntPtr GetModuleHandle(
                string lpModuleName);

            [DllImport("kernel32.dll", SetLastError = true)]
            public static extern IntPtr VirtualAllocEx(
                IntPtr hProcess,
                IntPtr lpAddress,
                IntPtr dwSize,
                uint flAllocationType,
                uint flProtect);

            [DllImport("kernel32.dll", SetLastError = true)]
            public static extern Int32 WriteProcessMemory(
                IntPtr hProcess,
                IntPtr lpBaseAddress,
                byte[] buffer,
                uint size,
                out IntPtr lpNumberOfBytesWritten);

            [DllImport("kernel32.dll", SetLastError = true)]
            public static extern IntPtr CreateRemoteThread(
                IntPtr hProcess,
                IntPtr lpThreadAttribute,
                IntPtr dwStackSize,
                IntPtr lpStartAddress,
                IntPtr lpParameter,
                uint dwCreationFlags,
                IntPtr lpThreadId);

            public static class VAE_Enums
            {
                public enum AllocationType
                {
                    MEM_COMMIT = 0x1000,
                    MEM_RESERVE = 0x2000,
                    MEM_RESET = 0x80000,
                }

                public enum ProtectionConstants
                {
                    PAGE_EXECUTE = 0X10,
                    PAGE_EXECUTE_READ = 0X20,
                    PAGE_EXECUTE_READWRITE = 0X40,
                    PAGE_EXECUTE_WRITECOPY = 0X80,
                    PAGE_NOACCESS = 0X01
                }
            }
        }       

        public static bool DoInject(
            Process pToBeInjected,
            string sDllPath,
            out string sError)
        {
            IntPtr hwnd = IntPtr.Zero;
            if (!CRT(pToBeInjected, sDllPath, out sError, out hwnd)) //CreateRemoteThread
            {
                //close the handle, since the method wasn't able to get to that
                if (hwnd != (IntPtr)0)
                    WINAPI.CloseHandle(hwnd);
                return false;
            }
            int wee = Marshal.GetLastWin32Error();
            return true;
        }

        private static bool CRT(
            Process pToBeInjected,
            string sDllPath,
            out string sError,
            out IntPtr hwnd)
        {
            sError = String.Empty; //in case we encounter no errors

            IntPtr hndProc = WINAPI.OpenProcess(
                (0x2 | 0x8 | 0x10 | 0x20 | 0x400), //create thread, query info, operation
                //write, and read
                1,
                (uint)pToBeInjected.Id);

            hwnd = hndProc;

            if (hndProc == (IntPtr)0)
            {
                sError = "Unable to attatch to process.\n";
                sError += "Error code: " + Marshal.GetLastWin32Error();
                return false;
            }

            IntPtr lpLLAddress = WINAPI.GetProcAddress(
                WINAPI.GetModuleHandle("kernel32.dll"),
                "LoadLibraryA");

            if (lpLLAddress == (IntPtr)0)
            {
                sError = "Unable to find address of \"LoadLibraryA\".\n";
                sError += "Error code: " + Marshal.GetLastWin32Error();
                return false;
            }

            IntPtr lpAddress = WINAPI.VirtualAllocEx(
                hndProc,
                (IntPtr)null,
                (IntPtr)sDllPath.Length, //520 bytes should be enough
                (uint)WINAPI.VAE_Enums.AllocationType.MEM_COMMIT |
                (uint)WINAPI.VAE_Enums.AllocationType.MEM_RESERVE,
                (uint)WINAPI.VAE_Enums.ProtectionConstants.PAGE_EXECUTE_READWRITE);

            if (lpAddress == (IntPtr)0)
            {
                if (lpAddress == (IntPtr)0)
                {
                    sError = "Unable to allocate memory to target process.\n";
                    sError += "Error code: " + Marshal.GetLastWin32Error();
                    return false;
                }
            }

            byte[] bytes = CalcBytes(sDllPath);
            IntPtr ipTmp = IntPtr.Zero;

            WINAPI.WriteProcessMemory(
                hndProc,
                lpAddress,
                bytes,
                (uint)bytes.Length,
                out ipTmp);

            if (Marshal.GetLastWin32Error() != 0)
            {
                sError = "Unable to write memory to process.";
                sError += "Error code: " + Marshal.GetLastWin32Error();
                return false;
            }

            IntPtr ipThread = WINAPI.CreateRemoteThread(
                hndProc,
                (IntPtr)null,
                (IntPtr)0,
                lpLLAddress,
                lpAddress,
                0,
                (IntPtr)null);

            if (ipThread == (IntPtr)0)
            {
                sError = "Unable to load dll into memory.";
                sError += "Error code: " + Marshal.GetLastWin32Error();
                return false;
            }

            return true;
        }

        private static byte[] CalcBytes(string sToConvert)
        {
            byte[] bRet = System.Text.Encoding.ASCII.GetBytes(sToConvert);
            return bRet;
        }
    }
}

---

code for the main form

Code:

---

using System;
using System.Diagnostics;
using System.ComponentModel;
using System.Windows.Forms;

namespace InjectMe
{
    public partial class MainUI : Form
    {
        public MainUI()
        {
            InitializeComponent();
        }

        public static Process pApplication = null;
        public static string  sApplication = String.Empty;

        private void BtnBrowseDll_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Filter = "Dynamic Link Library|*.dll";
            ofd.FileOk += new CancelEventHandler(dll_FileOk);
            ofd.ShowDialog();           
        }

        private void dll_FileOk(object sender, CancelEventArgs e)
        {
            OpenFileDialog ofd = (OpenFileDialog)sender;
            TxtDllPath.Text = ofd.FileName;

            //now dispose of the object

            ofd.Dispose();           
        }

        private void BtnBrowseApp_Click(object sender, EventArgs e)
        {
            ProcFrm pf = new ProcFrm();
            pf.ShowDialog(this);
            TxtApp.Text = sApplication; //It will wait for pf to close, and before pf
            //closes, it will have set sApplication
        }

        private void BtnInject_Click(object sender, EventArgs e)
        {
            string sError = String.Empty;
            if (!Inject.DoInject(pApplication, TxtDllPath.Text, out sError))
                MessageBox.Show("The following error occured while injecting the \n" +
                    "dll into the application: \n" +
                    sError);
        }
    }
}

---

process form code

Code:

---

using System;
using System.Diagnostics;
using System.Windows.Forms;

//This class is used to select the process to inject the dll into

namespace InjectMe
{
    public partial class ProcFrm : Form
    {
        public ProcFrm()
        {
            InitializeComponent();
        }

        private void ProcFrm_Load(object sender, EventArgs e)
        {
            //populate the list box with all the running processes

            string sLstItem = String.Empty;

            foreach (Process p in Process.GetProcesses())
            {
                sLstItem = p.Id.ToString();
                sLstItem = sLstItem.PadLeft(8, '0');
                sLstItem = sLstItem + " " + p.ProcessName;
                LstProcs.Items.Add(sLstItem);
            }
           
            //now sort

            LstProcs.Sorted = true; //Some event handler somewhere sorts
            //the list box when this is changed to true
        }

        private void LstProcs_DoubleClick(object sender, EventArgs e)
        {
            BtnSelect_Click(null, null); //=D
        }

        private void BtnSelect_Click(object sender, EventArgs e)
        {
            if (LstProcs.SelectedIndex == -1)
                return;

            string sPID = String.Empty;
            string[] saData = ((string)LstProcs.Items[LstProcs.SelectedIndex]).Split(' ');
            sPID = saData[0]; //it'll be "xxxxxxxx procname"
            int iPID = int.Parse(sPID);

            MainUI.pApplication = Process.GetProcessById(iPID);

            if (MainUI.pApplication != null)
                MainUI.sApplication = MainUI.pApplication.ProcessName;

            this.Close(); //done with this form
        }
    }
}

---

So can some one plz help me :(:confused: and tell me the problem/problems with it and fix them?and tell me how to fix them?