SQL Server :: Working With Two Tables Using Stored Procedures?

I am trying to insert some data into a table and update another table using the same stored procedure but it doesn't work.

ALTER PROCEDURE dbo.new_suppliers_orders_add_products
@SupplierOrderID int,
@ProductID int,
@OrderQuantity int,
@NewOrderQuantity int
AS
INSERT INTO SupplierOrderLine(SupplierOrderID, ProductID, OrderQuantity) VALUES (@SupplierOrderID,@ProductID, @OrderQuantity)
UPDATE Products SET QuantityOnOrder = @NewOrderQuantity WHERE ProductID=@ProductID
RETURN

Is it any way it can be done or I need to use two separate stored procedures?