I do not have the box but it was Fact Plus I think?
you could call your gyno and schedule an apt to confirm to see if it is a pos. it's always possible to get false negs....but from what i understand rare for a false +. orrrr you could wait till after a/f is due and retest then.
I know myself that i Have had evaporation lines befor but I could always tell they weren't the real thing. If you tested with different kinds and they were negitive then it was probably evaporation lines but that doesn't mean you aren't PG It took 6 weeks for me to get a BFP with my daughter. And I had a blood test with my son that was Neg. but I still was. They only other thing I can think of is that maybe the one with the line required a smaller amount of HCG then the other ones do you still have the box?
Well when i look at it i do say a very very faint line. But Im not for sure. I would wait intill the weekend and test again. Good Luck :o)