I got the same card with the same headset.

Firstly, make sure that your mic is plugged in the pink connector (right of the green one, which is the line out for your headphones).

Secondly, you gotta go in the eax console, click on the karaoke tab, make sure the "enable karaoke" box is checked. Then you gotta unmute the mic at the bottom right corner of the window. It's muted by default when you install the creative software. After that, you can uncheck the "enable karaoke" box.