Your ssh client ask an X11 redirection but you cannot run it on a remote machine
You do not have the right installation. You should install xauth.
You can install xauth with:
apt-get install xbase-clients
now try again like: ssh -X -l username remotehost
You should be able to start X programs. If you dont, check your variable $DISPLAY. Also check the debug output of ssh -v -X -l username remotehost.
Here you should find the line: "Requesting X11 forwarding with authentication spoofing"
About the Author
Wim Peeters is electronics engineer with an additional master in IT and over 30 years of experience including time spent in support, development, consulting, training and database administration. Wim has worked with SQL Server since version 6.5. He has developed in C/C++, Java and C# on Windows and Linux in different European countries and different European languages. He writes knowledge base articles to solve IT problems and publishes them on the Lubby Knowledge Platform where he is one of the most important contributors and the main developer.