Hi I have used them and only once have I got a definite positive where the test line is as dark as the control line.. Having said that I am not sure if and when I ovulate so that could have been the only time.. These testa are confusing aren't they!! Maybe buy a digital one?? I wont go that way as they are expensive and it's definitely hit and miss for me, but if you know when you should be ovulating it might be worth it for you?? Good Luck