APEX

I am using custom authentication with APEX 4.1.1 and I want to display custom error messages on the login page if authentication fails. In my authentication function I'm using apex_util.set_authenication_result to set a result code (code below). I've tried to use the apex_util.get_authenication_result on the login page to hide and show custom messages but it's not working. I don't believe the apex_util.get_authenication_result is actually obtaining the result? Am I doing something wrong? Is there a better way?

FUNCTION verify_user(
    p_username VARCHAR2,
    p_password VARCHAR2
  ) RETURN BOOLEAN
  IS
    v_ctr      NUMBER;
    v_id       NUMBER;
    v_attempts NUMBER;
  BEGIN

    SELECT COUNT(1) INTO v_ctr FROM users_tbl 
       WHERE username = TRIM(UPPER(p_username)) 
       AND password = utl_raw.cast_to_raw(dbms_obfuscation_toolkit.md5(input_string => p_password || TRIM(UPPER(p_username))));

    IF v_ctr = 1 THEN

      SELECT user_id INTO v_id FROM users_tbl WHERE username = TRIM(UPPER(p_username));
      UPDATE users_tbl SET login_attempts = 0 WHERE user_id = v_id;
      APEX_UTIL.SET_AUTHENTICATION_RESULT(0);
      RETURN TRUE;

    ELSE
      SELECT COUNT(1) INTO v_ctr FROM users_tbl WHERE username = TRIM(UPPER(p_username));

      IF v_ctr = 1 THEN

        SELECT user_id INTO v_id FROM users_tbl WHERE username = TRIM(UPPER(p_username));

        SELECT login_attempts INTO v_attempts FROM users_tbl WHERE user_id = v_id;
        IF v_attempts > 5 THEN
          APEX_UTIL.SET_AUTHENTICATION_RESULT(2);
          RETURN FALSE;
        ELSE
          UPDATE users_tbl SET login_attempts = login_attempts + 1 WHERE user_id = v_id;
        END IF;

      END IF;

      APEX_UTIL.SET_AUTHENTICATION_RESULT(1);
      RETURN FALSE;

    END IF;

  END verify_user;

Thanks,
Mark