TV Tuner video recording – no sound

Hi, I just installed a Mercury TV Tuner card, and as recommended in the manual, connected the Audio Out of the TV Tuner card to the Line In of my Sound Card (Creative SoundBlaster, I think). Anyway, in the settings of the TVR software version 3.0 that I got along with the card, I can select Audio Source as None or Line-In. The manual says I should select Line-In while Recording from cable TV. Anyway, I do the recording and all I get is silence which turns to hissing if I turn the volume way up and some faint mumbling of voices. I don’t know why but the sound isn’t getting recorded. Please please please help.

Thanks,

Kamal