Why no surround sound?

Does anyone have any pointers that may help me get surround sound to work with my Soundblaster 128 PCI with my polk amr90 speakers? Yes, they are hooked up correctly(I even reversed the wires to see if i had it in wrong). The two front speaker and the sub woofer are fine, but the two rear speakers barely make any noise at all. you have to put your ear up against them to be able to barely hear whatever game or song i'm playing. i can hear them hissing ever so slightly. i went into control panel(sounds and multimedia) and chose surround sound speaker setup. What else can i try? thanks in advanced.