Ramana,
you are grouping and aggregating the data on the wrong level, before the UNION operation.
From what you described you want to perform the SUM/GROUP on the result of the UNION operations.
Thus your query should look similar to this:
select NOTINFO, OBJECT, SUM (MHSDUR), SUM(...)
from ( SELECT NOTINFO,...
UNION ALL
SELECT NOTINFO...
UNION ALL ...)
group by NOTINFO, OBJECT...
In fact you could simply surround your existing query with the additional aggregation since SUMming up the already summed up durations will still yield valid results.
- Lars