Center speaker problem?

i own a Creative T6060 5.1 speaker set along with sound blaster audigy value sound card.all speakers work fine except the center one. i have the right drivers from CD and enabled all 5.1 features like eax,cmss,b redirection etc;but all speakers deliver good output while center one delivers low output while testing and while playing games,movies the dialogues come from front left n right speakers and the center one is dead.i don't know whether it's a hardware problem or software problem?but when i checked the audio port on sub woofer wit other speaker cable,it works and all the ports work fine!