Meaning: One of two things has happened: (1) You modified route objects in such a way that the support does not have a valid location with respect to input route objects; or (2) The Assembly selection rule is not available or not registered correctly.
Recovery: If the support does not have a valid location with respect to input route objects, reselect appropriate new route inputs or reposition the support on the existing route input. If there is a problem with the Assembly selection rule, you may need to re-register the rule.