Doors being disabled despite arguments provided

Hey
I've just discovered the Single and Type commands. I'm trying to set it on a garage door but each time I type it I get "Automatic Doors closing is now disabled" Any ideas?

Thanks

What did you type in?
/ad s 20
/autodoor single 20

both the same result. 
I don't know. In my tests, all commands worked.
"Automatic Doors closing is now disabled" means you only type in /ad