Have you configured networking correctly in the virtual machine ?
I don't use VM, but I do use SSH and VNC on BT5.
I just installed tightvncserver and xtightvncviewer
Then do:Code:apt-get install tightvncserver xtightvncviewer
And set you password.Code:vncpasswd
Now when you run "vncserver" you should be able to connect. By default the new desktop is :1 on port 5901. You need to enter this in combination with you ip(LAN) in you vnc viewer application.