I have never got a positive with an OPK even the cycle I fall pg with my DD so I think it is a little bit obvious that I did O. With OPK's you can miss the LH surge and they don't work for all women. Whil some women get positives with no problems.
From memory (not 100% sure though) I think they suggest you do the test around 2.30pm, don't drink for 2 hours before to avoid diluted urine and if you get two lines to retest later that evening. Are you using any other methods for watching your cycle/ovulation?
Hopefully you want need to use these again and best of luck with your test this morning.