gridview update exception

Error: **No value given for one or more parameters.**

string updateSql = "UPDATE [RateCenters] " + "SET [RateCenterName] = @RateCenterName, [Province]= @Province, [QuantityThreshold] =@QuantityThreshold  " + "WHERE [RateCenterID]=@RateCenterID";


        protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
        {
            GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];

            DropDownList ddl = (DropDownList)row.FindControl("DropDownList2");

            TextBox rateCenterName = (TextBox)row.FindControl("txtRateCenterName");

            TextBox quantityThreshold = (TextBox)row.FindControl("txtQuantityThreshold");

            Label ratecenterid = (Label)row.FindControl("Label1");

            OleDbConnection conn = new OleDbConnection(ConfigurationManager.ConnectionStrings["DBConnection"].ToString());

            OleDbCommand cmd = null;

            try
            {
                conn.Open();

                cmd = new OleDbCommand(updateSql, conn);

                cmd.Parameters.Add("@RateCenterID", OleDbType.Integer).Value = Convert.ToInt32(ratecenterid.Text);
                cmd.Parameters.Add("@RateCenterName", OleDbType.VarChar).Value = rateCenterName.Text;
                cmd.Parameters.Add("@Province", OleDbType.VarChar).Value = ddl.SelectedValue;
                cmd.Parameters.Add("@QuantityThreshold", OleDbType.Integer).Value = Convert.ToUInt32(quantityThreshold.Text);


                cmd.Connection = conn;
                cmd.ExecuteNonQuery();

                GridView1.EditIndex = -1;
                GridView1.DataBind();
            }

            catch (OleDbException ex)
            {
                throw (ex);
            }

            finally
            {
                cmd.Dispose();
                conn.Close();
                conn.Dispose();
            }
        }