HCM 9.0 Left Out Join Issue

Hi. I seem to have problems with Left Outer Joins in a Query using 9.0.  All I am trying to do is pull two staging tables together with a left outer join (Current HR data and benefit data) and output where Benefit Progam is blank. It gives me no results but I know that there is someone with blank info because I created them to test.

I was told that 9.0 had problems with left outer joins and I should use a subquery not in list but Im having problems understanding how to do this, even by reading some guidance notes.

Wondered if someone could advise: