I read:
Xlib: connection to ":0.0" refused by server Xlib: No protocol specified
Application initialization failed: this isn't a Tk applicationcouldn't connect to display ":0.0"
as suggested in the earlier answer, if you want to connect to an xserver that was started by another user the brute force method would be to run xhost + before starting the application, if this is via a remote login you might have to export your DISPLAY environment variable manually. look the manpage for xhost pls,
HTH
x