when i use upstream traceability of warehouse product lot

warehouse -> traceability ->production lots -> form view -> select demo-> open -> click on upstream availability

got this error message

Traceback (most recent call last):
  File "/home/rmu/source/server/trunk/openerp/osv/osv.py", line 120, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/home/rmu/source/server/trunk/openerp/osv/osv.py", line 175, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/home/rmu/source/server/trunk/openerp/osv/osv.py", line 163, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/home/rmu/source/addons/trunk/stock/stock.py", line 1439, in action_traceability
    value=self.pool.get('action.traceability').action_traceability(cr,uid,ids,context)
  File "/home/rmu/source/addons/trunk/stock/wizard/stock_traceability.py", line 50, in action_traceability
    view_id = cr.fetchone()[0]
TypeError: 'NoneType' object is unsubscriptable