hearing the fetal Heartbeat?

Question by Becca O:
hearing the fetal Heartbeat?
Today I was screwing around at work (labor and delivery unit) with the doppler monitor and was trying to find the heartbeat (15 weeks along) and couldn’t find it. I’m no professional, and I’ve heard the heartbeat three times before at the doctor.

Should I worry, or is it just my skill? I only tried for about ten minutes, and it wasn’t a “fetal heartbeat doppler”.

I don’t think I should worry because I wasn’t really positioned right. I don’t know, any advice?
Thanks.