I've been having the same thing, I have only been using OPKs for a little over a month since Ive only just started keeping track of my cycle, but i use two OPKs everyday, i thought this way there would be no way id miss a positive, but so far no luck, i have little bit of pain and CM around cd13 so i was sure this was it, but no positive!! I also only get a faint control line. Well not tooooo faint, but certainly not strong, ive also never had any kind of second line on it, i read that most people have a second line but until its stronger than the control line it doesnt count.... well id be happy to see any kind of second line D: