Only showing "High"

I purchased the Clearblue Fertility Monitor a couple months ago. During the past 2 month of use it has shown "high" beginning on day 6 until I begin my cycle. According to the lab work completed by my doctor I am ovulating. My doctors office also informed me that they have had a number of these same complaints with this same device. This device was over $200 and this is very disappointing for something of this cost to not work. Is there something that can be done about this?