Your game probably uses the DirectInput API. That would be my default expectation for most modern 3D games.
http://msdn.microsoft.com/library/default.asp?url...nput/html/diov.asp
quote:
Apart from providing services for devices not supported by the Microsoft Win32 API, Microsoft DirectInput gives faster access to input data by communicating directly with the hardware drivers rather than relying on Microsoft Windows messages.
SendKeys() stuffs the Windows message loop, which sits at a higher level than DirectInput, so they are never seen by your game.
Unfortunately, I don't know off the top of my head how you would go about simulating keys so they are recognized by DirectInput.