>>>Thanks, that's what I got working, but what was wrong with my logic/syntax?
>>
>>The error comes from this condition
>>receipts.policyheaderfk = policyloans.policyheaderfk
>>
>>This field can not be used in a query if we're not grouping by it. You can add it into GROUP BY to avoid the error or do the change as I did.
>
>So why did my test query work? I think I had also tried adding in the Group By but got a different error.
>
>This is not terribly important as I got it working, but I'm just trying to understand/learn.

In your test query you have this field in the GROUP BY. If you remove it from the GROUP BY, you most likely will get the same error.