Authorised home devices for Sky Go

I have a iMac and a MacBook Pro sat next to each other. On the iMac Sky Go works fine. On the MacBook Pro, I get error code 1410 when trying to watch a Sky Sports football match and cannot watch the same thing I can watch on the iMac! I am logged in to Sky correctly on both machines and recently deleted and re-installed the Sky Go app on the MacBook. I can even log onto Sky Go successfully on my iPhone!! If I can only use 2 devices, I would prefer the two computers and drop the iPhone but I can't see how to do this. I can watch other channels on Sky Go on the MacBook but not Sky Sports!!!