Error when running URL returned by GET_RUN_FUNCTION_URL for form INVIDITM

Hi All,
I'm trying to launch form INVIDITM with an URL returned by PL/SQL API FND_RUN_FUNCTION.GET_RUN_FUNCTION_URL. To generate appropriate URL I call GET_RUN_FUNCTION_URL like the following:

DECLARE
  P_FUNCTION_NAME VARCHAR2(200);
  P_RESP_APPL VARCHAR2(200);
  P_RESP_KEY VARCHAR2(200);
  P_SECURITY_GROUP_KEY VARCHAR2(200);
  P_PARAMETERS VARCHAR2(200);
  P_OVERRIDE_AGENT VARCHAR2(200);
  P_ORG_ID NUMBER;
  P_LANG_CODE VARCHAR2(200);
  P_ENCRYPTPARAMETERS BOOLEAN;
  v_Return VARCHAR2(2000);
BEGIN
  P_FUNCTION_NAME := 'INV_INVIDITM_ORG';
  P_RESP_APPL := 'MSC';
  P_RESP_KEY := 'MANUFACTURING_SUPER_USER_ASCP';
  P_SECURITY_GROUP_KEY := 'STANDARD';
  P_PARAMETERS := 'org_id=208 item_id=216955';