Problem play AAC+ from my own plugin

I'm working on adding AAC+ support for my plugin - Digitally Imported XBMC addon 1.0
Whenever I try to play it, it says its a corrupt MP3 stream, and have come to the conclusion that it's most likely the mimetype thats wrong.

When it's a MP3 the item should be added to the list with this property set:
li.setProperty("mimetype", 'audio/mpeg')
With AAC I've tried using audio/mp4 as the mimetype instead, with no luck though.

When I put a .pls with AAC streams on a memstick and play it, it works flawless - but I can see in the log that it uses another player to play it back.

From "my" menuitem it uses (and fails with): CAudioDecoder
From a .pls on a memstick (and works): DVDPlayer

So how do I force my plugin to use the DVDplayer to playback AAC? Is setting a different mimetype enough?