N64 adapter for PJ64

I have just invested in a Rockfire PSX/USB adapter on installing it I used the Nrage input for rumble but evereytime I play a game after getting hit a few time the rumble wont go off in just keeps rumbling??? has anyone else had this problem?? I have searched all hte other post but cant find anything on it!! anyway help would be great

Danos

I have the other 3 rumble options but the direct rumble is grayed out and I cant select it???? I have tried the pad with other games like Crazy Taxi and it works on that!?? anymore ideas??

Thanks

oh and this might help. im using a Rockfire USB adapter with a PS2 pad