Help with PSP Action Replay

Hello,
I know it's more to do with accesories but here's my problem/annoyance.
Recently I purchased a Action Replay pack for my PSP 2002. It's the latest one that uses a transfer cable and PC software to work. I installed it fine but when I tried to use the codes on the PSP, they did not work. I followed the instructions carefully, I tried a couple of different games(and I am using the right region btw) and still nothing. Then I tried accesing the in-game AR menu that was described in the manual and found out that even that was not working.So as far as I can see, the program just fails to hook itself into my PSP for some reason. I tried e-mailing Datel but they weren't very helpful saying that they would update their website when a fix comes around.

The only thing I can think could be causing trouble is that I have GEN-B 5.50 Custom Firmware installed but I don't know if that's the cause.

Can anyone suggest any solutions(or has anyone experienced something similar)?