[Deji]

Actually this problem is usually an incompatible EXE. Problem is that SA-MP only supports certain files that run the internal code for GTASA. There are about 6 common breeds of gta_sa.exe out there. Multiply that number by 2 if you want to include cracks and modded .exe's (or stick with the original number if, like me, you only want to include cracks and modded .exe's ) and I estimate that SA-MP supports 4. Going by "Click here to download the downgrade patch." being in the wiki, SA-MP only supports 1.0 and there are two variants of that (actually, five to again include popular modified .exe's). There's US versions (4 in total) and EU versions (2). I reckon SA-MP supports these: 1.0US original, 1.0US no-cd, 1.0EU original, 1.0EU no-cd. I can only guess it supports EU as they are only a little different from the US variants internally.

You will have to ****** for 'one' of those gta_sa.exe versions, download and replace your .exe with it. I will not post a link and make any assumptions towards your disc-havingness level