This error seams to be related to a problem with the iRite instance name.
Here are a few things to double check.
Has the page you are trying to apply iRite to been saved within a Dreamweaver site?
Has it been saved as a dynamic page, either ASP, PHP or ColdFusion?
Is there a form on the page already?
Does it have a text box applied to it?
if you still have a problem, please send a copy of the page you are trying to apply iRite to.