Only 1 fertile day with clear blue ovulation

I've been using the clear blue digital ovulation tests for the last few cycles. TTC for 11 months now. For the last 2 cycles I have been testing and getting low fertility days and then one peak day and right back to low the next day and on. Never getting the high day and I am not getting more than one peak day. Has anyone else run into this problem? Any tips or ideas on what the problem could be....