SQL with PIVOT

Good afternoon:

i am having trouble running the below query with PIVOT in QC ALM 11.5 query builder. It say's "quality center couldn't run the query because it contains invalid statements". The purpose of this query is to display the bug records in a single row.

DECLARE @QUERY VARCHAR(4000)
DECLARE @BUG_ID VARCHAR(2000)
SELECT @BUG_ID = STUFF((SELECT
'],[' + STR(BUG.BG_BUG_ID)
FROM BUG
WHERE BUG.BG_SEVERITY = '1 - Critical'
AND BUG.BG_STATUS <> 'Fixed'
OR BUG.BG_SEVERITY = '2 - High'
AND BUG.BG_STATUS <> 'Fixed'
ORDER BY '],[' + STR(BUG.BG_BUG_ID)
FOR XML PATH('')
), 1, 2, '') + ']'

SET @QUERY =
'SELECT * FROM
(SELECT BUG.BG_BUG_ID
FROM BUG
) T
PIVOT (AVG(BUG.BG_BUG_ID) FOR BUG.BG_BUG_ID
IN ('+@BUG_ID+')) AS PVT'
EXECUTE (@QUERY)

Appreciate your help!

Thank You!