Cannot delete keyframes

I'm trying to understand why I run across this every so often. I am trying to make a simple blink animation, and the control I am using is "eyes closed" under Character/Pose Controls/Head/Face/Eyes/eyes closed. I made one instance of a blink on the timeline. I copied and pasted the same sequence a couple of times later in the timeline, but now I would like to change them, but I cannot delete them. I think I read one time that it is because there is another controller acting upon the eyes, other than in pose controls. I don't know where that would be because I can't find anywhere else that I can open and close the eyes. I'm sure it's not random and I am just doing something wrong, but to me it is random enough that I cannot figure it out. I was wondering if anyone has come across something like this and might have an idea what I could be doing wrong. Most of the time I have no problem deleting keyframes.