Env: AIX 5.3 / DB2 9.1

I am trying to use XMLAGG function but for some reason it fails. We just upgraded to DB2 9.1 hence i am not sure whether I need to turn on any other switch to use XMLAGG function. Please advice.

/tmp > db2 describe table tt

Column Type Type
name schema name Length Scale Nulls
------------------------------ --------- ------------------ -------- ----- ------
COL1 SYSIBM VARCHAR 10 0 Yes

1 record(s) selected.

/tmp> db2 "select * from tt"

COL1
----------
welcome
DB2
9.1

3 record(s) selected.

/tmp> db2 -tvf q2.sql
SELECT XMLSERIALIZE( XMLQUERY('/fn:data(COL1)' PASSING XMLDOCUMENT( XMLAGG(XMLELEMENT(NAME "COL1", COL1))) ) AS CLOB(50) EXCLUDING XMLDECLARATION) FROM TT
SQL0104N An unexpected token "PASSING XMLDOCUMENT( XMLAGG(XMLELEMENT(NA" was
found following "ERY('/fn:data(COL1)'". Expected tokens may include:
"<space>". SQLSTATE=42601