Fortissimo III 7.1 - lost center channel

I installed a Hercules Fortissimo III 7.1 sound card and dumped a Creative Audigy card. I have Inspire 5.1 Digital 5700 speakers. I now cannot get the Fortissimo to recognize my center channel or subwoofer. Any ideas on the problem?? I get sound on all four other speakers, just not the center or subwoofer.

Thanks for the reply! Plug configuratin and settings checked over several times. Only setting I have not tried yet is "small speakers." The Inspire speakers have a Digital DIN input,connected to the sound card with a miniplug to din connector. I am wondering if the fortissimo is not compatible with digital inputs on speakers since the analog inputs work fine. I have also doublechecked the integrity of the outputs on the card,by plugging in my front speakers to the center channel output and did obtain sound. Any othr ideas are most appreciated! Thanks for your time.