When calling an object using a web service, if there is a pop-up in the user interface, it will return a message like this, and the call will fail.  This looks like the allocation window is popping up.  I normally try to enter the transaction manually, from the screen in X3, and this will tell you specifically what the window is.  To override this, you will need to add custom code to suppress the window when theGWEBSERV value = 1, but make sure it won't cause any other issues if you do this. I also sometimes wrap the call around a custom subprogram, and call the import template for the object from the web service.  The import templates normally get around these types of errors.