Is JInitiator already installed ?
Also, under “Edit”->”Preferences” go to the “Runtime” tab and check the value for “Application Server URL”.
It should be something similar to “http://127.0.0.1:8889/forms/frmservlet”.
Try to put that URL directly into Internet Explorer and see what happens. You should see an “Installed Successfully !” message. Make sure the address and port are correct.