Expected X11 driver: /usr/lib/gnuplot/gnuplot_x11

[Per Zetterberg]

Dear All,

I installed first version 2.8 and then 2.1 of octave. Then I installed
gnuplot. When trying to plot "plot([1 2 3])" I get the error message
"Expected X11 driver: /usr/lib/gnuplot/gnuplot_x11" ?

I am running xubuntu as my laptop is a bit old.

I am a complete newbie (maybe appearent)

Any help would be appreciated
BR/
Per Zetterberg