Is it the UK PAL version by any chance? If it is, that version does not work on any emulator at all at this time. ISOs don't work either because there are no patches for this version. The reason it won't work is because of the intense copy protection that was put on it. If this is the version you have, better get a PSX or PS2 to play it on. Sorry.
To apply the patch you need this tool: http://www.megagames.com/psx/files/pdx-ppf2.zip
and CR-RWIN: www.goldenhawk.com
Then with CDRWIN copy your CD(extract disc/track sectors),then with PPF-o-matic,select the ISO and the patch corresponding to the CD(one per CD),then you just have to push apply,it will tell you if the patching was succesfull.
Then either you burn the disc or play directly from the ISO.