Can No Longer Access On Demand Shows

I tried to access some "On Demand" shows and got the message that I need to Subscribe to the channel to access the On Demand shows. However, I AM already subscribed to the channels and have always been able to access the On Demand shows for those channels, until yesterday.  So I can watch the channels, live. But when I try to watch some On Demand shows, I get the message that I need to upgrade my subscription to include those channels. What's going on?