Can anyone helpme to find solution in this error?

When i want change to the Diagram View in the Panel Technical>Workflows>Worflows i get this error. 

Traceback (most recent call last):
File "/opt/openerp/server/openerp/http.py", line 470, in dispatch result = self._call_function(**self.params)
File "/opt/openerp/server/openerp/http.py", line 294, in _call_function return checked_call(self.db, *args, **kwargs)
File "/opt/openerp/server/openerp/service/model.py", line 113, in wrapper return f(dbname, *args, **kwargs)
File "/opt/openerp/server/openerp/http.py", line 291, in checked_call return self.endpoint(*a, **kw)
File "/opt/openerp/server/openerp/http.py", line 638, in __call__ return self.method(*args, **kw)
File "/opt/openerp/server/openerp/http.py", line 337, in response_wrap response = f(*args, **kw)
TypeError: get_diagram_info() takes exactly 9 arguments (8 given)

Thanks a lot.