Exec procedure as parsing schema, not APEX_PUBLIC_USER

Question

We have a package with a procedure:
CREATE OR REPLACE PACKAGE XGN4.xgn_generator$pck
AUTHID DEFINER AS
PROCEDURE cr_tab(tab_id IN NUMBER);
END;
CREATE OR REPLACE PACKAGE BODY XGN4.xgn_generator$pck
PROCEDURE cr_tab(tab_id IN NUMBER)
IS
BEGIN
execute immediate('CREATE TABLE test(......)');
END;
END;
When I call this procedure from apex, it's always executed as 'APEX_PUBLIC_USER', but it should be as the parsing schema 'XGN4'.
I thought 'AUTHID DEFINER' should do the trick (it's standard when you're not using AUTHID), but it looks like it has no effect on APEX...
Anyone?

Answer 1

Ok Scott, you are right.
I used sys_context('USERENV','CURRENT_USER') to identify the user and it's the right parsing schema (XGN4).
But why won't my code execute right in apex when it does straight from SQL-DEVELOPER (or another tool)?
Eg:
In toad: EXEC packagename.procedure(parameter);
in Apex: begin; packagename.procedure(parameter); end;
the procedure contains an execute immediate('alter tabel ...') and will do his job in the first case, but returns an error insufficient privs from apex.