Ado.net VB stored procedure update issue

I am filling a table from an SP with the following columns:-

SELECT     Sotrn.SotrnId,  InvoiceName + ' (' + crctl.CrcAbrev + ')' AS Customer
, Sotrn.No_Units as Units, Sotrn.Unit_Price AS Price, Slrep.RepName, Hauliers.Haul_Desc AS Haulier, [Depot Name] as [Dispatch_From],
                  sohed.KeyDate as Dispatch, Potrn.PotrnId, Potrn.Ord_Units
FROM         Sotrn INNER JOIN Etc Etc

This works fine.

I then created an Sqlcommand to update this as follows:-


        dim cmdUpdateOrders as New SqlCommand
        Try
            cmdUpdateOrders.Parameters.AddRange(New SqlParameter() _
              {New SqlParameter("@Units", SqlDbType.SmallMoney), _
               New SqlParameter("@Price", SqlDbType.SmallMoney), _
               New SqlParameter("@SotrnId", SqlDbType.Int), _
              New SqlParameter("@PotrnId", SqlDbType.Int)})
            cmdUpdateOrders.CommandType = CommandType.StoredProcedure
            cmdUpdateOrders.Connection = CON
            cmdUpdateOrders.CommandText = "CtsWtUpdateSOrds"
        Catch ex As Exception
            MsgBox("Error " & ex.Message & " in Setup_StockOrder_Query - CmdUpdateOrders ")
        End Try


The SP for the update is as follows:-

ALTER PROCEDURE [dbo].[CtsWtUpdateSOrds] @Units SmallMoney, @Price SmallMoney, @SotrnId Integer, @PotrnId Integer
AS
UPDATE Sotrn SET No_Units = @Units, Unit_Price = @Price WHERE SotrnId = @Sotrnid
UPDATE Potrn SET Ord_Units = @Units  WHERE PotrnId = @Potrnid

but when I try the following code:-

 Try
            AD.UpdateCommand = cmdUpdateOrders
            AD.Update(DS, "StockOrderAlloc")
        Catch ex As Exception
            MsgBox("Error " & ex.Message & " in cmdUpdateChanges_Click")
        End Try

I get :-

Error Procedure or Function CtswtUpdateSOrds expects parameter '@Units', which was not supplied.

I think I am nearly there.

Any ideas anyone?