Yes, I would consider that to be negative for ovulation. It is a strangely dark negative, but I would say it's negative. It really does need to be as dark as the control line or darker. It is normal to get dark ish but not quite dark enough lines just before you get AF just because your hormone levels rise a bit at the end of your cycle. But is there any chance you could be pregnant? Opks will start to turn positive in early pregnancy because luteinizing hormone and hcg are very molecularly similar. That's dark enough that I would probably consider taking a pregnancy test unless I was sure there was no chance I could be pregnant. It could totally just be a late cycle LH rise, but I would be curious.