"High Fertility" 9 days in a row - is test broken?

My average cycle length is about 31 days. I began using the advanced digital ovulation tests on day 17 of my cycle, and took a test every day for 9 days (on the 9th day I took two). All 10 tests have read High Fertility. Is there something wrong with the test? I took 9 of the tests first thing each morning, and the 10th test in the afternoon, just to see if I would get a different result. But none were Low or Peak - all High. Has anyone else ever had the same result 9 days in a row? I bought a new test kit, but haven't tried it yet.