just wasted several hours trying to set up remote recording. every time i tried to register it came up "invalid username". with help from the sky help desk it was eventually discovered that the registration process has a few bugs and if your username has special characters in it then you cant register!(mine has - in it). to get around this you need to delete your mobile number from your main user account. then create a new user without any special characters e.g. "fredblogs " . give this your mobile number.
now you can register with this on sky+. but of course if you want to remote record via web then you have to log into this "fictitious" account to do it.