Opk results

Not sure whereto post this, but since im over 30 and ttc ill write here. I have the digital opk from clearblue with the smiley face. Friday morning i got a smiley, when discarding the tester, i noticed no clear lines but a lot of breakthrough blue ink. I decided to retest later in the afternoon, and did NOT get a smiley. So onto Saturday morning, no smiley. This am a smiley again....decided to retest five hours later, and now NO smiley.....what is up? How can i get two surges, but no surges in between? I thought getting an easy read opk would help, looks like its not for me. Any input would be appreciated. Thanks