Black pixels looks brown exporting in h.264

I've created a comp in AE that renders very well .mov with Animation codec.

If I export it using h.264 coded in .mp4 (both from AE or Encoder), black pixels (default background) looks brown! This happens watching the video with QuickTime 7 and VLC 2. I have other players (such as WMP) that playbacks without any color problems.

I've tried to change color profiles in AE but honestly the video looks good in AE itself.

Have you ever encountered this problem?

What could I try?