DBMS_XMLSCHEMA.generateschema gives ORA-22303: type not found

I just had someone call about this.SELECT DBMS_XMLSCHEMA.generateschema('your_schema','your_type') FROM DUAL;gives ORA-22303: type "your_schema"."your_type" not foundora-21700ora-06512 Just upper case your_schema and your_type -- YOUR_SCHEMA and YO...