Music suddenly stops on last picture with Photo Story

I just can't seem to figure out how to keep the music playing through the
whole video I'm trying to make. It reaches the last photo and then just
abruptly stops without the rest of the music. Do I have to set the "duration"
longer for each picture longer or something? I need to have the music play
right through for a video that I'm making for a wedding this Saturday and I'm
stumped! Can somebody please help me if they know what to do? I'd really
appreciate it.