I want to unblock channel I have previously blocked?

I set up a custom guide for my husband. There a few channels that I need to unblock so I can add them into his custom guide. I have gone to these channels and a que comes up asking me to unblock now I choose that option and place my PIN number to unblock. It does unblock it for the current show but when the next shows comes on, it blocks it again and I have to go through the whole thing again.  What do I do to get these channels into the custom guide?
I am so confused…