Hey Michelle,

I have been using them for about 6 months now. I have never received two dark lines.

Howver I do know that I am ovulating.

Firstly your best bet would be as soon as you start seeing two lines, you should start testing 3 times a day.

Some people only show two dark lines for a few hours so atleast if you test three times a day you should catch it.

if not, (i always test three times a day and have never had 2 dark lines) you may be like me where it is not strong enough to detect however you still ovulate.

Hang in there girl!