PLS-00306 WRONG number or types of arguments in call to XMLAGG

This a bug in Oracle. This error is thrown when you use ORDER BY clause with XMLAGG in PL/SQL.

Work Around: Remove the ORDER BY Clause

Funny part is, the SQL will work fine in SQLPLUS, but when you use in PL/SQL it will throws the above error.

Versions confirmed as being affected: 9.2.0.2 to 9.2.0.6

This bug is fixed from 9.2.0.7 onwards