Outer Joins and no data with calculations

I have two queries; Production and rejections. Since there will always be production, I joined it to rejections using Outer. The next step is to take rejection data and do a calculation with the production data. I can do this for 99% of the data except when I get production data, but no rejection data. The output on the rejection will be "NA". I need to take the NA and replace it with a 0. In the join (Join_Prod.Output) on the outgoing links, I placed the following code...

Both of which still return an "NA"

if(Join_Prod.Output{/Rowsets/Rowset/Row/REJQTY}=="NA",0,Join_Prod.Output{/Rowsets/Rowset/Row/REJQTY})

or

if(Join_Prod.Output{/Rowsets/Rowset/Row/REJQTY}>=0,Join_Prod.Output{/Rowsets/Rowset/Row/REJQTY},0)

I noticed that joins that only return one row of data the code works. In this case, I have roughly 5 rows and if there is an "NA", it will not compute the code correctly.

What am I doing wrong?