Can't hear mic, VU Ok

Everything I input, even the mic, is Ok. But, I can't hear the mic over the speakers or head phones. It's like the through/output signal is very weak. Yet, the VU's register fine and it records fine. Playback is fine. I need to hear myself singing in my headphones to get the grove. I can't even get the mic to sound through the speakers. When I put my phones into the "powered output," I can hear it, so there is a signal there, just very weak. How is this possible? Why don't the output correspond to the VU meters?

It just sounded like "my car won't start" question because it seems impossible. Here are the specs:

Software Program: Music Creator 2003
Sound Card: VIA AC’97 Audio (Wave)
Mix Board: 4 channel Folio Note Pad, Soundcraft
Desktop Speakers: Polk Audio
Mic: Sure
Headphones: Realistic

Objective: To play stereo music tracks already recorded while recording a new vocal track.
Problem: Any input for the mic has a very low through output. I have compared this output to a guitar, CD player, and keyboard. Everything corresponds the output with the VU meters except the mic, no matter whether it is patched directly or through the mix board. Anything plugged into the mix board also corresponds with the VU meters, except the mic. Even when used simultaneous. I tried playing a CD player through the mixer with the mic on stereo input on one track. The VU meters register, but the mic through signal is very weak, even though it is registering very high on the VU meter.

I solved this problem by pulling up the consol in MC and turning the main fader way down. This does not effect the mic volume passing through track 3. By patching into another small amp with a headphone jack, I balanced the weak mic through signal with a weak play tracks 1 and 2 signal on output. By turning up the output amp volume, I can hear through the headphones to sing in the groove.

So, how is this possible?