custom grid view for candidate application

Summary:

I am having problem displaying the union seniority date. Although I already found a documentation related to implementation from my last inquiry here, but it is not working.

Actions done:

Already created an Extensible flexfield.

Already added in grid but no values.
Sql created in Extensible flexfield.

SELECT to_CHAR(SN.SENIORITY_DATE,'YYYY-MM-DD') FROM PER_SENIORITY_DATES_F SN, PER_ALL_ASSIGNMENTS_M ASG
WHERE ASG.PERSON_ID = :{PARAMETER.PERSON_ID}
AND SN.SENIORITY_DATE_CODE = 'SWCB_UNIONSENIORITY'

Requirement to be displayed: Union Seniority date.