3.40OE-A issue

I have put 3.40OE-A firmware on my psp. I have put some games on my memory card but I each time I try and start a game, I get an error message saying cannot start game (800203321). Can anyone help?? Is there a setting I need to alter or something like that???

Types? ISO or PBP (ISO TALK NOT ALLOWED!!!)
IF EBOOT.PBP MAKE SURE IT IS IN THE GAME150 IF THE EBOOT IS MADE FOR FW1.50!