Burning downloaded iso and bin ps2 files

Could somebody please tell me why my ps2 copies that I downloaded from the internet doesn’t work on my playstation. I have done some copies from original games and they work perfectly, but every game that I downloaded doesn’t seem to work. I use nero for burning, and have a slidecard in my ps2 purchased from www.mod-chip.com.

Slidecards are shit and downloading games you do not legally own is even bigger shit…