What hack are you trying to inject? Do you have Direct X Redist / C++ Redist / NET Framework installed? You need them to view most hack menus.
I use PerX and ran as admin, and did everything -- Injected to Engine.exe I started Combat arms as Admin and and PerX says injected successfully, but when I load into Combat Arms and press 'Insert', the hack bar doesn't show up, doesn't crash or anything. Just nothing pops up. I am using Windows 7 64bit.
What hack are you trying to inject? Do you have Direct X Redist / C++ Redist / NET Framework installed? You need them to view most hack menus.