>>Are you missing an alias for the derived table?
>>
>>It should work OK - what is your error?
>
>Oh my . . . I just discovered another problem that I have to deal with first. With my test data, the first query returns 1 record, the second returns 179, but when I combine them with the UNION I only get 19.Coincidentally, 19 is the number that should return when the rtastatus field is aggregated. I thought perhaps the WHERE clauses were causing this but that is not the case. I also changed the aliases in the second SELECT so they were not reused but that also made no difference. Any idea what gives? I was expecting 180 records.

UNION and UNION ALL are two different things. This is a hint, I am not telling you more, but you should figure this out.