Ovulation test error?

I have been taking the Clearblue Easy digital ovulation test for 3 months. I always start on day 7 just to make sure don't miss my window. I have gotten the smiley face detecting my LH surge on day 7 or 8. Could be this accurate each month. I don't get my cycle until day 27 or 28. How can this be possible?? Any suggestions appreciated. Thanks