I had to make the following change
from:
,DECODE(COALESCE(t1.REOPEN_FLG,T2.REOPEN_FLG), '1', 'true', '0', 'false') AS REOPEN_FLG
to:
,COALESCE (DECODE(t1.REOPEN_FLG, '1', 'true', '0', 'false'), DECODE(t2.REOPEN_FLG, '1', 'true', '0', 'false')) AS REOPEN_FLG
as I was getting the following...