I'll try sending you an invitation. You should get an email telling you you have received an invitation on SB. Sign yourself into SB and then click on 'new messages' in the top right hand corner - then click on my message to you. Once it's open, it will ask if you want to accept the invitation. Click 'accept', and then I think you have to click 'add to friends'.
I've got to go out now, but I'll check later to see if we've cracked it. If not, we'll keep trying, so don't worry.