How to set Display for local ip on RHEL5/OEL5

1. Check the current display setting:
echo $DISPLAY
:0.0
2. With this xclock will work.
3. Now suppose we have local m/c ip-address: 10.1.12.55
4. Set the display as
export $DISPLAY=10.1.12.55:0.0
5. Xclock
Can't open display on 10.1.12.55
6. set DISPLAY to :0.0
export DISPLAY=:0.0
7. Start gdmsetup, go to security , un-check the "Deny TCP connections to Xserver"
8. reeboot or restart gdm :
gdm-restart
9. Now set display as localip:
export DISPLAY=10.1.12.55:0.0
10. run xclock