Clearblue Digital Ovulation Tests trouble and confusion..

So looking back i realize i may have already ovulated as one of my tests from CD 20 seems to be the darkest opk ive had all month. However, i remember taking a digital clearblue ovulation test that day and it was negative despite the opk being a decent positive. The test didnt even have a flashing smiley face... has anyonw else had any issues with these digital tests? I usually only use them to confirm ivw ovulated but it looks likw it gave me a bad read for the first time..? Any advice helps! Thanks ladies.