There are a couple of problems here:
The DISPLAY is in the format :. so you were probably told to set it to ":0.0" but this is wrong as that is the default server on the local machine.
When you connect using ssh (with X11 forwarding enabled), the DISPLAY variable will be set by ssh to something like localhost:10.0 so you shouldn't have to set the DISPLAY variable anyway (unless something like your .bashrc changes it).