Dependent Coverage End date Fast Formula is not returning correct End dates for each Dependent

Hi, We have a requirement to End date the Dependent Coverage End date when Child turns age 21.

It is returning same value for all Dependents irrespective of the Child age or for other dependents . Below is the code of the same.

DEFAULT FOR PER_PER_DATE_OF_BIRTH is '1951/01/01 0:00:00'(date)
DEFAULT FOR BEN_PIL_LF_EVT_OCRD_DT is '1950/01/01 00:00:00'(date)
DEFAULT_DATA_VALUE FOR PER_PER_CONT_REL_CONTACT_PERSON_ID is 0
DEFAULT_DATA_VALUE FOR PER_PER_CONT_REL_CONTACT_TYPE is 'NA'

l_eff_date = trunc(GET_CONTEXT(EFFECTIVE_DATE,'1950/01/01 00:00:00'(date)))

l_age = 0