ORA-19011 in outer query but not in derive table

Question

Here is the function I am using in the inner query and it executes against the whole data set without error with a group by.

RTRIM(XMLAGG(XMLELEMENT(E,LOCATION_CD,';').EXTRACT('//text()'))
    )AS PRAC_LOC

However when I bring it up into the outer query I get the error message 19011. Is there another coding strategy I could use to not get this error message? Do you think a CTE to isolate the query then join into the CTE would work? It's a log table so there are multiple entries so I guess I could isolate the join with the date = select max(date).

I was looking at all the other topics in regards to this error but nothing mentioned the error in just the outer query.

Here is a sample of the derived table

LEFT OUTER JOIN
(
    SELECT 
    PLACE_ID --Single Grouping on Place_ID
    , RTRIM(XMLAGG(XMLELEMENT(E,LOCATION_CD,';').EXTRACT('//text()'))) AS PRAC_LOC
    FROM GEOTABLE
    GROUP BY PLACE_ID
) GEO
ON GEO.Place_ID = P.Place_ID

Answer 1

Adding the .getCLOBVal()) function to the end of the XML script allowed the script to run and use it in the outer query from my derive table.

RTRIM(XMLAGG(XMLELEMENT(E ,TLOCATION_CD || ',')).EXTRACT('//text()').getCLOBVal())