Anyone ever had false negatives?

Hi I'm curious about something. I'm 10 days past missed period and I never miss a period. I've taken tests and they say negative. I've had multiple friends say that they had friends and family get negatives all the way up to the day they gave birth. So my question is... Has anyone personally had that happen? I'm hoping to get into the DR this week. 
Oh one more thing. I miscarried sept. 2011 at 7 weeks. And would get a negative than a positive over and over again. Don't know if that has anything to do with this time.