the gameshark i have came preloaded with some but when i select some codes and begin to play the screen stays blank , does it matter that i have the greatest hits gta:vc ? any help would be very apperciated

Yes, it does matter. When a 'Greatest Hits' version of a game comes out, the game is always a bit different. Usually none of the codes for the original game would work with the new one. An example would be Resident Evil: Outbreak. In the codes list, theres RE: Outbreak and RE: Outbreak version 4. People call the 'Greatest Hits' "version 4" because if you look at the back of the disk, after the long code, theres a space and then the number 4. Also, the code on the "spine" of the case (I don't really know what to call it), has a code under the name. It usually starts with "SLUS" and then a game number but, the 'Greatest Hits' version adds a "GH" after the number.

What this means is that you must find a list of codes for your specific game now (the Greatest Hits version).