I think that I had a problem with one of the reality checks. I couldn't breath through my nose when I pinched it in a dream. But since this had happened twice before, and I was unsatisfied, I did looked for some writing(which appeared right behind me ), and did another reality check. That one worked.

I think it has something to do with whether you believe it'll work or not, or some reality checks just don't work with some people. Still, it's an interesting point.