warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'audio_play'

I get this on my page after updating this morning. Any idea whats causing it? I happened to upgrade drupal to 6.4 from 6.3 as well.

I think because of this error, Its not allowing embedded player to play, it just says buffering, and when you click on download, it just goes to blank page.