ran into the same prob myself
ok
If you want to transfer a player for nothing - in other words, for an 'unregistered' slot, I found this works well:
1) Look at the position, on the team's list, of the player you want to transfer
2) If he is *anywhere* near the top, go ahead and select him
3) Now, when you go to pick the team where he is to be transferred, choose his team yet again
++ so you should have your player being transferred to the same team, eg AC Milan --> AC Milan ++
4) To be safe pick the dead last player on your team's '2nd' list and this will switch the player to be transferred from where he is to the very bottom
5) Once he's moved, scroll down and select him again, and now you should be able to swap him for anyone's 'unregistered' spot
6) Make sure when you're finished to check the teams' formations in case they are all dicked up
hope this helps
