NATURALLEFTOUTERJOIN

Hi wyanjaspew 

Delete DEFINE 

In line 14 you need to specify the name of the column like "Product Name", 'Product'[Product]. Same foe line 15

Delete lines 18 and 19

Replace EVALUATE in line 21 with RETURN 

As tamerj1 mentioned, deleted "DEFINE" and replace EVALUATE with a RETURN. Basically, the key is, you're defining a variable which can then be passed as an argument and returning the named variable.