There is also a point when you are going through the initial configuration of the MD that this issue can arrise from.
when you are prompted to log into http://www.schedulesdirect.org/
you will see the guide\tv listing that you selected from their website when you setup your account. If you simply hit enter on the keyboard here, you will return to the screen listing your TV tuner but the checkbox next to it will remain blank.
If you repeat the steps and after logging in physically click on your listing data (even though it looks selected) you will then return to the screen listing your tv tuner and it will have a check mark in the box.
I missed this the first couple times I went through the install as i simply hit enter and recieved the same error message you described until I did this. I couldnt for the life of me figure it out until my wife said click on it, but dont tell anyone that =P