I've had that happen twice now and everything was fine, he is just uncooperative. I hope that's all it is for you too, good luck.
Either the baby is positioned to where it can't be heard or a miscarriage has occurred. How far along are you?
good luck with your scan, i hope everything goes well and bub is fine :) like the other girls said, s/he is probably just in the wrong position :) dont stress too much
That happened until I was 20weeks. Everytime they would try to find it with the doppler and then just use the u/s.