I am working at Ubuntu 12.04 64bit. I have installed gnome-desktop and xrdp. Everything seems to be right but when Im trying to connect by Remote Desktop Connection in Windows 7 I can see this error picture:

I dont know why. I am connecting by IPv6 because in vps.me free users haven't no dedicated IPv4 only a shared but I can't connect anyway by shared I am totaly unskilled. Thats why I really need help tp set it up.
How to fix this ?