How to create custom column to a directquery dataset looking up to an import dataset

Hi everyone,

Tried to lookup a certain item row from a direct query dataset (Table 1 named 07A: Product Offering Codes) if it's also available in the second table which is an import table (Table 2 named ZZZ_Product Categories Masterfile) - this is for the purpose of checking for missing items on table 2.

I am receiving this error: "The column ___ either doesn't exist or doesn't have a relationship to any table available in the current context"; I know that Related formula is not possible with a direct query data set but I need an alternative that can be used for this. 

Screenshot of error:

Screenshot of relationship:

OPTIONAL NOTE:

I will use this to create a pie chart so that if I click on the missing items from the pie chart, the table will show all missing items to make it easier for me to get the list of missing items so I can update table 2 manually (Cause it is being maintained manually)