NetAnim: cannot connect to X server

Question

I have Ubuntu machine with NS3 and NetAnim installed.

When trying to run NetAnim with the command ./NetAnim, it does not run and I always get this message "NetAnim: cannot connect to X server".

I have been trying to fix it for two weeks but could not succeed. I tried many options including the following to run the server:

• xset -q
• ps -e | grep Xorg
• export DISPLAY=":0.0"
• apt-get install xserver-xorg xorg -y
• startx

However, the problem is still the same.

Appreciate your help as I am stuck in my work...