SQL & PL/SQL

Hello All,

I am using oracle database 10.2.0.4 in windows server.

I am doing data comparision for 2 set of query using the minus operator with same condition.
My 1st query is giving 23 rows and 2nd query is giving 20 rows. The output should be 3 rows, but I am not getting the same. It is returning null.

select WORK,WORK_UNIT,WORK_STR from WORK_GROUP
where WORK_UNIT=003
and WORK_STR=10
and WORK is null
MINUS
select WORK,WORK_UNIT,WORK_STR from WORK_GROUP@DBL_SOURCE
where WORK_UNIT=003
and WORK_STR=10
and WORK is null;

Any updates on the above query?

Thank You,

RKP