MP4 file has no audio

Got the new iPad and tried importing an MP4 video file via iTunes. When I play it on my iPad there is video but no audio. Tried playing it on AVPlayerHD but no audio either. The file plays fine on my laptop. Uploaded other MP4 files and the iPad played it.

Looking at the file, there were two audio files for two languages so I tried remuxing the file so it has one audio file but it still doesn't play.

Any ideas on this problem? Thanks.

 

Audio is AAC in 1536 kbps(!). I'm on a PC and tried it on MPC, VLC and SMPlayer. All three played the file.

Tried converting the AAC file to 160 kbps MP3 and muxing it with the video file but still no audio.