Installing game torrents

I like downloading games, lot easier than paying 4 them, at first it was working fine like it worked for oblivion, i burned it to a disk it installed and ran fine, but ive been trying to download different games, they download fine, install fine but when i try to play them it says that i need to insert the desk what am i doin wrong?

 

You probally need a cd crack just type in google the games name cd crack