Advanced Benefits coverage end date

Documentation in "Open Enrollment Processing and Plan Design Maintenance" states that I can use this query to confirm that enrollments are end dated so as to inactivate an obsolete plan in Advanced Benefits.

Select * from ben_prtt_enrt_rslt_f

Where enrt_cvg_thru_dt = ’31-Dec-4712’

And pl_id = ‘<enter pl_id>’;

I am still receiving records from this query, but am unsure what I need to change in my setup to allow these records to be end dated.  Some of the employees pulled back from this query are Terminated and have be de-enrolled from the plan, but the enrt_cvg_thru_dt is still as '31-DEC-4712'.  Any ideas?