I just played with ProntoEdit a bit to find out how to reproduce that problem.

I did so by selecting a non existent command from the database. I think you did that as well. It is fairly easy to do by accident. Or maybe whoever built the CCF you are trying to use did it.

Where did you get the CCF you are using? If there is a URL for it, and you tell me what command you're looking at, I can look to see whether it was already set to a nonexistent entry in the database or whether there's a real signal there and you clicked something you shouldn't have while trying to get to it.