xhost +: unable to display

Dear Linux and SAP Expert:

I am facing a problem, I want to install Oracle 9i on SUSE Linux, I need to use ora<sid> to install it, but when I use xhost +, i am prompted "xhost +: unable to display"

I have already set the followings:

setenv DISPLAY <my hostname>:0.0

xclock is also unable to display.

What can I do???How can I solve this problem?

Really really thanks for your all reply

Hisashi Glay