Error In The Stored Procedure

I am trying to swap two rows in a table .. I am stuck with this error since a long time.. can anyone guess where the problem is ? create procedure was working fine in query analyzer but when used it in the stored procedure. I am getting these .. can anyone help me out please ... Your help will be greatly appreciated.. UpdateRowsReorderUp is my storedprocedure ... and i am using MS Sql 2000 .. am I doing something really wrong which i'm not supposed to ?????

Thanks friends..
Procedure 'UpdateRowsReorderUp' expects parameter '@nextlowestsortID', which was not supplied.

CREATE PROCEDURE [dbo].[UpdateRowsReorderUp]

(

 @intsortID int,

 @nextlowestsortID int,

 @MemberID int
)
AS
 Select @nextlowestsortID=(Select Top 1 SortID from SelectedCredits where SortID<@intsortID order by SortID DESC)
 UPDATE SelectedCredits SET SortID= CASE
WHEN SortID = @nextlowestsortID then @intsortID
WHEN SortID = @intsortID then @nextlowestsortID ELSE SortID End
WHERE MemberID = @MemberID
SELECT * FROM SelectedCredits WHERE MemberID= @MemberID ORDER BY SortID
GO
**************
// this is my script on the page
 void moveup(Object s, DataListCommandEventArgs e)
  {

    objcmd= new SqlCommand("UpdateRowsReorderUp",objConn);

    objcmd.CommandType = CommandType.StoredProcedure;
   

    objcmd.Parameters.Add("@intsortID",intsortID);

    objcmd.Parameters.Add("@MemberID",Session["MemberID"]);

    objRdr= objcmd.ExecuteReader();

    dlSelCredits.DataSource = objRdr;

    dlSelCredits.DataBind();

    objRdr.Close();

    objConn.Close();

    BindData();
}