Help with Final Fantasy 4! Anyone?

I managed to get hold of an iso file of the FF4 collection for the PSP. However, when I load up the game, it says "the game could not be started" and goes back to the XMB. How do I make the iso work? Do I need to patch the iso file? I am using 5.00 m33 6 cfw. I have tried searching on the internet but unfortunately there seems to be no solution for this particular problem. Can anyone help? Points for anyone who could help the most! Thanks!