odd hpt question...

So I took a FRER and a dollar store test yesterday. BFN... Later I noticed a colored evap on the dollar store, so I decided to look at the FRER, so that I would recognize them. I took it apart held it up to the light, and saw no second line at all. I just wonder if maybe it (and others I have) may be bad. They are not expired, but they have been living in my bathroom for about a year. (they actually have the plastic as part of the strip which I have never seen since online) Do you think the heat/humidity could have hurt them?? I thought if you looked hard enough you could usually see some sort of indent, line??