.mp4 files in windows media player 11

I got the klite codec pack which allows me to play pretty much any format, even .mp4, FLAC, ogg, etc. but these formats don't show up in my music library.. I put them in my music along with all my other files in mp3 and wma formats and when I choose "add to library" wmp11 only recognizes the default formats.. is there a way to fix this? I don't really want to use any other program, I really like the WMP11 interface, I have a lot of music, the search and album art thing is really nice.