Can't login to Newfoundland with my old account

Hi there! I used to play in Newfoundland server with my Facebook account, then I haven't loged in for a month. When I came back I couldn't login to Newfoundland. It's force me to create a new account Northsile server, I choose my old nickname and it have been used @.@
Is there something wrong with my account? Can I log in to Newfoundland with my old account again?
My facebook profile: https://www.facebook.com/Nik9x
My email: nickky9x@gmail.com
My old nickname in Newfoundland: Nickky9x
My current nickname in Northsile: Nikky9x
P.s: Sorry for my bad English :)