Crystal Reports find value that does not exist in same table

Message

   I have a report that I am working on. 
It has a table in the report called Equipment.
The Equipment table has a column for Control # and a column for Parent Tag.
I am trying to find away to show All Parent Tag data that does not exist anywhere in the Control # data. 
Note: Parent Tag column may have empties and NULLS

I was easily able to pull the data in SQL with the following:
Select * from Equipment where ParentTag not in (Select ControlNo from Equipment) and ParentTag <>''.

I tried adding the Equipment table to the report a second time so I had Equipment and Equipment_1. I then did a left outer join from Equipment.ControlNo to Equipment_1.ParentTag, then in Select expert went to formula and added isnull({Equipment_1.ParentTag}).  Did not work.
Example of what I have:
__________________________________________________
ControlNo                   ParentTag
1111
1222
1333                          9999
1444
1555
1666                          1111
1777                          1333
1888                          2222
Example of what I want the end result to be:
___________________________________________________
ControlNo                  ParentTag
1333                         9999
1888                         2222

So I only want to show the data from ParentTag that does not exist any where in the ControlNo data.