Database Software

Hi all,

I try using case statement on select like that

SELECT
   xmlserialize(DOCUMENT
      xmlroot(XMLELEMENT(kdpwdocument,XMLATTRIBUTES(
                           'xxxxxxxx' AS sndr,
                           'xxxxxxxx' AS rcvr,
                           'xxxxxxxx' AS "xmlns",
                           'xxxxxxxx' AS "xmlns:xsi",
                           'xxxxxxxx' AS "xsi:schemaLocation"
                           ),
                           CASE WHEN REPO_STATUS=1 THEN
                                                                          xmlagg(
                                                    XMLELEMENT("regio",
                                                      XMLELEMENT("Inf",
                                                                  XMLELEMENT("Id",
                                                                             XMLELEMENT("PmryId",'1111'),
                                                                             XMLELEMENT("ScndryId",'1111')
                                                                            )
                                                                                      )
                                                                                      )
                                                                                      )
                          ELSE 
                                                                          xmlagg(
                                                    XMLELEMENT("regio",
                                                      XMLELEMENT("Inf",
                                                                  XMLELEMENT("Id",
                                                                             XMLELEMENT("PmryId",'0000'),
                                                                             XMLELEMENT("ScndryId",'0000')
                                                                            )
                                                                                      )
                                                                                      )
                                                                                      )
                                    END
                                      ) ,
              VERSION '1.0" encoding="UTF-8'
    ) AS CLOB) 
FROM REPO
WHERE 1=1
;

but i'm getting error:

00937. 00000 -  "not a single-group group function"

Any idea how I can change my query to get results? When I'm using group by repo_status, I'm getting two rows, but that isn't a good result for me