Upon termination of an approved leave of absence without pay, the employee member must return to the public service from which he or she was granted the leave. Credit will not be given for service or final average salary purposes unless the employee member actually returns to the payroll of such public employer and actually engages in the performance of his or her official duties. A return to the payroll of the State or a participating employer for the sole purpose of exhausting vacation, sick leave or other similar benefits, will not qualify the employee member for such credits. A failure to return to the service of the State or a participating employer upon termination of an approved leave of absence, as provided herein, will result in the revocation of the contingent approval previously granted.