My period started 12/29/11 and ended 1/2/11. I have a 28 day cycle. Since then I've been using CVS 20 day strip test at 11am daily... On 1/8/11 I also started testing at 6pm with First Response 7 day midstream kit. I am very confused as to why I go from a light line for the test line in the am to nothing in the evening... Yesterday was the only day that it seemed to even show on the First Response test but it was still not as dark as the control line. Are these tests reliable?