The HTTP error message on IIS is:
 

HTTP Error 405
405 Method Not Allowed
The method specified in the Request Line is not allowed for the resource identified by the request.
Please ensure that you have the proper MIME type setup for the resource you are requesting.

This (rather obscure) error message indicates that the DISPATCHER_URL of the generated HTML document templates (the ACTION attribute of the FORM tag) and the actual path to the Dispatcher program do not match. Correct this problem in one of three ways:

1. Correct the DISPATCHER_URL entry of the default Plex INI-file and regenerate the HTML document templates. Refer to Specify Path to Dispatcher in Plex INI-File section of the Document Template Generator/Implementation reference page.
2. Manually correct the ACTION attribute of each form in each Document Template  in the Websydian application.
3. Setup or correct the Web server alias for the Websydian application.