It is not uncommon for the monitor not to pick up a peak reading. I used one for a long time and found I only got a peak about 50% of the time. The reason being is you can only test once a day and around the same time. If your monitor doesn't see the E2 surge that preceeds the Lh surge, it will never go peak. It works a little different than a plain opk. Sometimes that surge is short and out of the test window for the monitor. If it's over by the time you test again, it will miss it.
This was refreshing! I've been TTC for 15 months. Broke down and bought the fertility monitor 3 months ago and have never reached "peak" fertility. I do get my period every month though. My cycle jumps from 25 days to 41 days. It makes sense what you said, hopefully I will see some success. It was also nice to find a blog that wasn't 4 years old!
The first month (May 2009) that I used the fertility monitor I got pregnant after showing two peak fertility days. Unfortunately I miscarried unexpectantly at 12 weeks. We are now trying again to get pregnant. I got my period exactly one month after my D&C and I've had two menstrual cyles since. This cycle (Sept. 09) my fertility monitor has shown no low fertility days only high fertility since my period ended. I am now on day 14 of my cycle and still not showing peak fertility although I swear too that I'm having ovulation pain. I hope that I'll show peak fertility in the next few days as I'm 41 years old and desperately want to have child #3.