Answer brand OPKs??

First time using OPKs 
So I started taking opk test since the day after my period ended but I'm not sure if this is considered a positve or am I getting closer to an oh surge.?  The control line on all the test I take show up super light. I looked online at images for comparison and my control line on all the test (from the answer brand) have all been lighter sometimes almost invisible. Becouse of this it has made it kinda confusing since all other control line images I see on Google are dark?? Also all other test I have take show a super thin dark line and lighter shading underneath?