Daker Color on export?

Hi all,
I'm almost afraid to ask this, cause you'll all realize how shoddy my editing is.

I have a promo video that I made. It looks good, and when I export it, it looks fine. But when I compress it for the web it makes the whole video much darker. Now here's the really weird part. I have two video tracks in the video. The second track is just a piece of a the wall that I put over an out lit behind the person talking. I did this to cover it up cause I didn't want to take the time to bring everything into color. The odd part is that when I compress the video, it makes the first track much darker, but the second track with the small wall patch stays the same. The question I really have is why is compressor making my video darker? And can I fix it?
Thanks

Caleb