When using average price for product I received the following error. How could this be fixed?

OpenERP Server Error Client Traceback (most recent call last): File "/opt/openerp/server/openerp/addons/web/http.py", line 204, in dispatch response["result"] = method(self, *self.params) File "/opt/openerp/server/openerp/addons/web/controllers/main.py", line 1128, in call_kw return self._call_kw(req, model, method, args, kwargs) File "/opt/openerp/server/openerp/addons/web/controllers/main.py", line 1120, in _call_kw return getattr(req.session.model(model), method)(args, **kwargs) File "/opt/openerp/server/openerp/addons/web/session.py", line 42, in proxy result = self.proxy.execute_kw(self.session._db, self.session._uid, self.session._password, self.model, method, args, kw) File "/opt/openerp/server/openerp/addons/web/session.py", line 30, in proxy_method result = self.session.send(self.service_name, method, *args) File "/opt/openerp/server/openerp/addons/web/session.py", line 103, in send raise xmlrpclib.Fault(openerp.tools.ustr(e), formatted_info)

Server Traceback (most recent call last): File "/opt/openerp/server/openerp/addons/web/session.py", line 89, in send return openerp.netsvc.dispatch_rpc(service_name, method, args) File "/opt/openerp/server/openerp/netsvc.py", line 292, in dispatch_rpc result = ExportService.getService(service_name).dispatch(method, params) File "/opt/openerp/server/openerp/service/web_services.py", line 626, in dispatch res = fn(db, uid, params) File "/opt/openerp/server/openerp/osv/osv.py", line 188, in execute_kw return self.execute(db, uid, obj, method, *args, *kw or {}) File "/opt/openerp/server/openerp/osv/osv.py", line 131, in wrapper return f(self, dbname, args, *kwargs) File "/opt/openerp/server/openerp/osv/osv.py", line 197, in execute res = self.execute_cr(cr, uid, obj, method, args, *kw) File "/opt/openerp/server/openerp/osv/osv.py", line 185, in execute_cr return getattr(object, method)(cr, uid, args, *kw) File "/opt/openerp/server/openerp/addons/stock/wizard/stock_partial_picking.py", line 121, in default_get moves = [self._partial_move_for(cr, uid, m) for m in picking.move_lines if m.state not in ('done','cancel')] File "/opt/openerp/server/openerp/addons/stock/wizard/stock_partial_picking.py", line 155, in _partial_move_for partial_move.update(update_cost=True, **self._product_cost_for_average_update(cr, uid, move)) File "/opt/openerp/server/openerp/addons/purchase_landed_costs/stock.py", line 65, in _product_cost_for_average_update self._logger.debug('res stock_partial_picking %s', res) AttributeError: 'stock.partial.picking' object has no attribute '_logger'