X11 forwarding request failed on channel 0

While trying to use the program `gnuplot` on my VPS, I encountered this error:

Failed to initialize wxWidgets.
warning: Too many axis ticks requested (>8)

To fix this, I tried the -X parameter:

[email protected]:~$ ssh -X [email protected]
X11 forwarding request failed on channel 0
Last login:

I checked the server side file /etc/ssh/sshd_config:

[[email protected]] ~ #grep -in --color X11Forwarding /etc/ssh/sshd_config
62:X11Forwarding yes

So that wasnt an issue.

I needed to install the package `xauth` on the server side.

apt-get install xauth

Now, retrying:

[email protected]:~$ ssh -X [email protected]
Last login: Fri Jul  5 21:01:30 2013 from 106.66.117.168
/usr/bin/xauth:  creating new authority file /root/.Xauthority

Welcome to dragon, root!

It worked.
Reference: StackExchange