I am a bit obsessive, so I have been testing with the CB advanced digital, the regular CB digital, and the non-digital OPK. With my last pregnancy the regular CB digital worked for me, btw. So here's what I found. Yesterday morning I received my first flashing smiley on the advanced and a negative on the non digital opk. But I've never caught my surge with fmu and you can't test multiple times a day with the advanced, so I went out and bought the regular CB digital. At 2 pm I tested with the regular CB digital and got a smiley. I backed it up with a non digital opk and had a definite positive (test line was darker than control). Last night I tested again with the regular CB digital just for fun and I still had a smiling positive. This morning I tested with CB advanced again... Flashing smiley...high again, not peak, right? With the same FMU, I used the regular CB digital and non digital OPK and both were negative. So I think the advanced missed my surge. I definitely recommend the old CB digital.