Error while evaluating document

Hi,

I'm attempting to enrich data from a table that has a 1-N relationship with my recipient table into my delivery so I can make the content conditional on a number.

This is my workflow:

I have a list of my mailable customers which has an additional query to select only those who met the criteria.

In my enrichment, I only want 1 column, where the "brand code" is equal to "BE"

The columns I'm enriching with are the one's below...

Here's the advanced join condition so I only pull data where the brand code is equal to BE.

I think my logic is correct however when I try pull in a field I've enriched I get this error in the Preview.

Can anyone see where I'm going wrong?

Any help would be greatly appreciated.

Thanks

Kevin