How to set DISPLAY variable

I am attempting to install ebusiness 12r using rapidwiz

I get the following error

I am using putty and I have x11 enable forwarding

I am using xmanager and have that started

so what is the correct way to set the display variable

I am doing the following

export DISPLAY=localhost:0.0

[oracle@erieoracle /]$ ./mnt/stage/startCD/Disk1/rapidwiz/rapidwiz

Rapid Install Wizard is validating your file system......
CMDDIR=//./mnt/stage/startCD/Disk1/rapidwiz
Rapid Install Wizard will now launch the Java Interface.....

Exception in thread "main" java.lang.InternalError: Can't connect to X11 window server using 'localhost:0.0' as the value of the DISPLAY variable.