Get OnHand Quantities using API

PROCEDURE get_onhand_quantity (p_item_id IN NUMBER, p_organization_id IN NUMBER, p_onhand_qty OUT NUMBER)
  IS
   x_return_status         VARCHAR2 (50);
   x_msg_count             VARCHAR2 (50);
   x_msg_data              VARCHAR2 (50);
   v_item_id               NUMBER;
   v_org_id                NUMBER;
   v_qoh                   NUMBER;
   v_rqoh                  NUMBER;
   v_atr                   NUMBER;
   v_att                   NUMBER;
   v_qr                    NUMBER;
   v_qs                    NUMBER;
   v_lot_control_code      BOOLEAN;
   v_serial_control_code   BOOLEAN;
BEGIN
   v_qoh := NULL;
   v_rqoh := NULL;
   v_atr := NULL;
   v_lot_control_code := FALSE;
   v_serial_control_code := FALSE;
   -- Set the org context
   --fnd_client_info.set_org_context (83);
   fnd_global.apps_initialize (17267, 20539, 401);
   -- Call API
   inv_quantity_tree_pub.query_quantities (
   p_api_version_number => 1.0,
    p_init_msg_lst             => 'F',
    x_return_status            => x_return_status,
    x_msg_count                => x_msg_count,
    x_msg_data                 => x_msg_data,
    p_organization_id          => p_organization_id,
    p_inventory_item_id        => p_item_id,
    p_tree_mode                => apps.inv_quantity_tree_pub.g_transaction_mode, -- or 3
    p_is_revision_control      => FALSE,
    p_is_lot_control           => v_lot_control_code,  -- is_lot_control,
    p_is_serial_control        => v_serial_control_code,
    p_revision                 => NULL,        -- p_revision,
    p_lot_number               => NULL,           -- p_lot_number,
    p_lot_expiration_date      => SYSDATE,
    p_subinventory_code        => NULL,    -- p_subinventory_code,
    p_locator_id               => NULL,           -- p_locator_id,
    -- p_cost_group_id            => NULL,       -- cg_id,
    p_onhand_source            => 3,
    x_qoh                      => v_qoh,      -- Quantity on-hand
    x_rqoh                     => v_rqoh,           --reservable quantity on-hand
    x_qr                       => v_qr,
    x_qs                       => v_qs,
    x_att                      => v_att,  -- available to transact
    x_atr                      => v_atr    -- available to reserve
   );
   dbms_output.put_line ('api return status is '||x_return_status);
   DBMS_OUTPUT.put_line ('On-Hand Quantity: ' || v_qoh);
   DBMS_OUTPUT.put_line ('Available to reserve: ' || v_atr);
   DBMS_OUTPUT.put_line ('Quantity Reserved: ' || v_qr);
   DBMS_OUTPUT.put_line ('Quantity Suggested: ' || v_qs);
   DBMS_OUTPUT.put_line ('Available to Transact: ' || v_att);
   DBMS_OUTPUT.put_line ('Available to Reserve: ' || v_atr);
EXCEPTION
   WHEN OTHERS
   THEN
      DBMS_OUTPUT.put_line ('ERROR: ' || SQLERRM); 
  END get_onhand_quantity;