bug with reports made with report_creator on the web

I did a personnal report after installing the module report_creator. I use the last official release.
It works fine with the GTK client but not with the web client:
I got this message:
A problem occurred in a Python script. Here is the sequence of function calls leading up to the error, in the order they occurred.
 /usr/lib/python2.5/site-packages/CherryPy-2.3.0-py2.5.egg/cherrypy/_cphttptools.py in _run(self=<cherrypy._cphttptools.Request object at 0xa26efac>)
  119 applyFilters('before_main')
  120 if self.execute_main:
  121 self.main()
  122 break
  123 except cherrypy.InternalRedirect, ir:
self = <cherrypy._cphttptools.Request object at 0xa26efac>, self.main = <bound method Request.main of <cherrypy._cphttptools.Request object at 0xa26efac>>
 /usr/lib/python2.5/site-packages/CherryPy-2.3.0-py2.5.egg/cherrypy/_cphttptools.py in main(self=<cherrypy._cphttptools.Request object at 0xa26efac>, path='/tree/open')
  262 self.object_path = '/' + '/'.join(object_path[1:])
  263 try:
  264 body = page_handler(*virtual_path, **self.params)
  265 except Exception, x:
  266 if hasattr(x, "args"):
body undefined, page_handler = <function open at 0xa44833c>, virtual_path = [], self = <cherrypy._cphttptools.Request object at 0xa26efac>, self.params = {'id': u'2', 'model': u'base_report_creator.report'}