iPhone - Playing badformat 3gp file using MPMoviePlayerController is not giving error

I'm using MPMoviePlayerController to play few videos.

But unfortunately, one of the video whose extention is 3gp is in bad format. On click of a button, the video is played and using some calculation, 开发者_开发问答different videos are selected.

When the badly formatted video is selected its displaying a message "The movie format is not supported" which I don't want to show. I want to select another video if the format of video is wrong.

I implemented "MPMoviePlayerContentPreloadDidFinishNotification". I'm handling error condition as well as successfull condition. Why am I not receiving error in this notification when the video format is wrong?