Extending CO with SETWHERECLAUSE causes error

In R12.1.3 of EBS,  extending the OrigSysUserLOVCO Controller and placing a SETWHERELCLAUSE() to add additional filter to the NtfUSERVO VO Object that controls the user LOV for assigning people as part of Vacation Rules setup.  Additional condition is to prevent Requisition Approvers from reassigning to others who don't already possess same Job level.  Had previously added the additional conditions to VO where clause by extending it but discovered that same VO is used elsewhere during Requisition Forwarding where this change is not desired.  Hence, trying to affect behavior at Controller level.    Searching the problem suggest a bind variable issue but