I see you state that your username is a two-word name. This could be the problem. Please try using your Mac's username as displayed in the terminal
One other thing you can try:
-Go into system preferences - sharing. Disable "Screen Sharing" and "Remote Management" (if enabled).
-Get RemoterFusion (
http://remoterfusion.rafsoftware.com). During installation it will set up screen sharing for you
-Open RemoterFusion, go to the "Setup" tab, the username you need to use is displayed under "Username".
You don't need to use RemoterFusion beyond this point, you could uninstall it. It's just a way to make sure screen sharing/remote management is setup right, and that you get the username.
Raf.