I\'m not sure what\'s going on here, mostly because I\'ve never used this function, but when I use the listagg function on our Oracle 11g database it gives me an ORA-00923 F
Are you using 11.1 or 11.2? LISTAGG was introduced in 11.2, it was not available in 11.1.
Your SQL statement looks valid to me in 11.2. But you'd get an error in 11.1 and ORA-00923 would seem like a reasonable error in 11.1.