I got a fix for your problems here!!!
Don't use a script executor on these scripts. Use Cheat Engine (latest version):
First, you want to navigate to your ArmA 2: Operation Arrowhead directory and create a folder there called "scripts" and put my Vehicle Scripts in it.
Open up Cheat Engine and ArmA II: CO. At the main menu of ArmA II: CO, you want to go to cheat engine and find the process "arma2oa.exe". Once you have selected this, you want to change the value type to "String" and search for:
private ["_dummy"]; _dummy = [_this,"onload"] execVM "\ca\ui\scripts\dedicatedServerInterface.sqf";
Once you find the value, double click it to add it to the window at the bottom and double click the value to edit it to:
private ["_dummy"]; _dummy = [_this,"onload"] execVM "\scripts\[nameofvehicleyouwanttospawn].sqf";
Head back in game and press Right Shift + P and around 10 meters behind you should spawn whatever vehicle you picked.
Note: You need a Shift+P enabled server.
---------- Post added at 10:40 PM ---------- Previous post was at 10:39 PM ----------
And just tested the scripts again and they work as charm.