I am using a client running ubuntu 11.04 to connect to Sun Solaris app-server to run an application called XTOP.
On the ubuntu client, I type
xhost +
then telnet to the remote server, then
export DISPLAY=<hostname>:0.0
then I start the application XTOP

A warning is then displayed:
Warning: Your DISPLAY variable is wrongly setup !

Then I get:
/usr/openwin/bin/xmodmap: unable to open display 'petter-VPCEH1S1E:0.0'

Does anyone have any idea how to solve this ? I do not understand why it says that the display variable is wrongly setup and why the display cannot be opened.