I’d been using inexpensive amazon purchased opk sticks - never had an issue or trouble reading them. I also successfully conceived my son using them.

Well I ran out and got some at the drugstore- generic brand because they were so expensive!

My question is that I took a test, it came up negative (vf line) after the recommended time. Then I left it on the counter and saw about two hours later that the line was significantly darker. My other tests said to disregard anything after 10 minutes - do you think these are the same?