Trying to implement a VPD policy but got the following error ORA-20001

Question

hey good day,
I'm trying to implement a VPD policy to my application. After I have performed the below task (Label 1) in oracle 10g database. When I'm about to access my application page in ApEx 3.2.1 I got the following error
ORA-20001: get_dbms_sql_cursor error ORA-28110: policy function or package CHARLES.VPD_PREDICATE has error
any form of assistance will be greatly appreciated.
thanks in advance
Label 1
USER is "VPD_ADMIN"
SQL> create or replace context empnum_ctx using set_empnum_ctx_pkg;
Context created.
SQL> CREATE OR REPLACE PACKAGE set_empnum_ctx_pkg IS
  2    PROCEDURE set_empnum;
  3  END;
  4  /
Package created.
SQL> CREATE OR REPLACE PACKAGE BODY set_empnum_ctx_pkg IS
  2    PROCEDURE set_empnum IS
  3     emp_id NUMBER;
  4    BEGIN
  5     SELECT EMPNUM INTO emp_id FROM CHARLES.INSTRUCTOR
  6     WHERE upper(username) = nvl(v('APP_USER'), USER);
  7     DBMS_SESSION.SET_CONTEXT('empnum_ctx', 'empnum', emp_id);
  8
  9    EXCEPTION
10      WHEN NO_DATA_FOUND THEN NULL;
11    END;
12  END;
13  /
Package body created.
SQL> create or replace package vpd_policy as
  2    function vpd_predicate(object_schema in varchar2 default null, object_name in varchar2 default null)
  3     return varchar2;
  4  end;
  5  /
Package created.
SQL> create or replace package body vpd_policy as  function vpd_predicate(
  2   object_schema in varchar2 default null, object_name in varchar2 default null)
  3     return varchar2 as
  4
  5      BEGIN
  6     if (USER = 'ADMIN') and (v('APP_USER') is null) or
  7        (USER = 'MICHAEL.GRAY') and (v('APP_USER') is NULL) then
  8       return '';
  9     else
10       return '(
11             exists (
12                     select  "INSTRUCTOR"."EMPNUM" as "EMPNUM",
13                             "INSTRUCTOR"."FIRSTNAME" as "FIRSTNAME",
14                             "INSTRUCTOR"."LASTNAME" as "LASTNAME",
15                             "LOAD"."COURSEID" as "COURSEID",
16                             "COURSE"."CREDIT" as "CREDIT",
17                             "COURSE"."HPW" as "HPW",
18                             "LOAD"."CAMPID" as "CAMPID",
19                             "LOAD"."YR" as "YR",
20                             "INSTRUCTOR"."POS" as "POS",
21                             "INSTRUCTOR"."USERNAME" as "USERNAME",
22                             "INSTRUCTOR"."DEPARTMENT_NAME" as "DEPARTMENT_NAME",
23                             "LOAD"."SEMESTER" as "SEMESTER"
24                     from    "COURSE" "COURSE",
25                             "INSTRUCTOR" "INSTRUCTOR",
26                             "LOAD" "LOAD"
27                     where   "INSTRUCTOR"."EMPNUM"="LOAD"."EMPNUM"
28                     and     "LOAD"."COURSEID"="COURSE"."COURSEID"
29                     and     department_name = (
30                                     select department_name from departments
31                                     where upper (assigned_to) = nvl(v(''APP_USER''),USER) )
32                                     )
33
34                     or upper(username) = nvl(v(''APP_USER''), USER)
35                                                ) ';
36
37     END IF;
38  END vpd_predicate;
39  END vpd_policy;
40  /
Package body created.
SQL> begin
  2  dbms_rls.add_policy(
  3  object_schema => 'charles',
  4  object_name => 'load',
  5  policy_name => 'Loading Policy',
  6  function_schema => 'charles',
  7  policy_function => 'vpd_predicate',
  8  statement_types => 'select, update, insert, delete');
  9  end;
10  /
PL/SQL procedure successfully completed.

Answer 1

ORA-20001 isn't an Oracle error message it was coded into your application by a developer: Look it up.
Consider too the following:
EXCEPTION
   WHEN NO_DATA_FOUND THEN NULL;so if the employee identifier is not found ... is this really what you want? If an employee isn't valid shouldn't you know it?