Crystal Reports How to Select Non matching rows between 2 tables

Message

   I ran out of ideas on this simple problem and I am turning to you Crystal gurus.  I have two tables. I need to select the rows that are not matching between those.

Table1                  Table2
Material    Cost        Material     Price
1001         $9         1002         $12
1002         $9         1003         $12

As you see, Materials 1001 and 1003 did not match between the two tables. And that is the list I need. I decided to create two sub reports and combine them. So, I tried this for Report1 : Link material between Table1->Table2 with left outer Join. 

I selected the setting, Default values for nulls. I got this as expected :
Table1-Material   Table2-Material
1001              <Blank>
1002              1002

When I try to filter out the 1002 - which is common - by using the select expert {Table2.Material} = "", it did not work..  

I was expecting only this : 1001                     <Blank>  

But I get this as a result :
1001                     <Blank>
1002                     <Blank>

Any ideas... Please help.