I have used them and have had no problem. Whether you are ovulating or not, a lot of times there will be color on the test line of an OPK. A line does not mean positve on OPK's its only postive when the test line is as dark or darker than the control line.
I used them along with another OPK and got a positive with both on the same day. Then I took the test stick from the digital out of the wand tio compare the two and the line was darker on my regular OPK than it was on the digital. That is probably because the sensitivity in each tests are different. I am not sure what the sensitivity on the tests is, but I will look it up and post. Regardless if I had just had to use the lines to decide whether I was ovulating or not, I would have thought the digital was negative but that wasnt the case, it was positive according to the smily face and the regular OPK backed that up.
With all that being said I tested several times a day with both the digital and the regular. When removing the digital test stick, the test line was equal to or darker than the control line on all days I had the LH surge except for the first test.
I would say you are not ovulating yet. If you were I think the digital would show a postiive and if it didnt for some reason the line on the actual test stick would still be darker line than that line in the picture you show. When I got the line on the first digital that said positive, even though I would have thought it negative if I was just using the stick, it was still darker than that line.
Thats my experience with those. I hope this helps you!
Edit : If your temps say you ovulated it is possible that you missed your surge. Not all women can get an LH surge on OPKs. There are plenty of threads on here where women have said they didnt but they do get temp rises. I think youre good as long as you BD