Gta san andreas for ps2 not working?

I just bought a used version of the game yesterday (used was all i could find and afford) and it won't work! i've cleaned it with an alcohol swab, wiped it on my shirt, ran it under water and dried it with a clean towel, blew on it and wiped it off, and it still won't work. Any suggestions before i just give up and exchange it for a new disk?