Hi. I did a couple of pregnancy tests and both appeared negative (a vertical line in the control window and no vertical line in the test window). There was however also a very fine line running through both windows horizontally that eventually disappeared. I was just wondering if this is normal. I am assuming that it was there because of the moisture and I'm worrying about nothing. On the diagram in the instructions it indicates that it should be a vertical line in both windows for a positive result. Hope I've explained this clearly!