I recently purchased a Zoom H4N. I imported a wav file that was sent to my PC, and imported it into my H4N. I set up an external mic and can hear the track playing as I test the vocal. When I press record, the backing track goes off and I hear only my exterior mic. Maybe not to clear. It's all new. Just wanted to lay a vocal, no effect, to send to him for mixing. Can someone help me?