Getting not a group by function for the query in BIP report

Getting :

ORA-00979: not a GROUP BY expression for the query in BIP report.

Below is my query

I am getting this errow while adding any sub query(Payment Terms). In the group by expression I have mentioned all the select columns, still I am getting the error.

SELECT DISTINCT
CASE
WHEN Substr(vl.legal_entity_name, -4) = '_FIN' THEN
Substr(vl.legal_entity_name, 1, Length(vl.legal_entity_name) - 4)
ELSE vl.legal_entity_name
END "Entity Name",
CASE
WHEN Substr(bu.bu_name, -4) = '_FIN' THEN Substr(bu.bu_name, 1,
Length(bu.bu_name) - 4)
ELSE bu.bu_name