[MissingRecordException: Requested record cannot be found by key

<<pre lang="xml">ig:WebDataGrid
                                                ID="MeterReadingDataGrid" runat="server" Height="205px" Width="794px"
                                                style="margin-bottom: 11px" onrowadding="WebDataGrid1_RowAdding"
                                                DataKeyFields="MachineID" onrowupdated="MeterReadingDataGrid_RowUpdated"
                                                onrowupdating="MeterReadingDataGrid_RowUpdating"
                                                 EnableAjaxViewState="False"  >
                                                <Behaviors>
                                                    <ig:ColumnMoving>
                                                    </ig:ColumnMoving>
                                                    <ig:ColumnResizing>
                                                    </ig:ColumnResizing>
                                                    <ig:Selection CellClickAction="Row" RowSelectType="Single">
                                                    </ig:Selection>
                                                    <ig:Activation>
                                                    </ig:Activation>
                                                    <ig:EditingCore Enabled="true" AutoCRUD="false">
                                                        <Behaviors>
                                                            <ig:CellEditing Enabled="true">
                                                            <EditModeActions MouseClick="Single" />
                                                            <ColumnSettings>
                                                            <ig:EditingColumnSetting ColumnKey="MachineDescription" EditorID="MachineID" />
                                                            <ig:EditingColumnSetting ColumnKey="LastDayMeterReading" EditorID="MachineID" />
                                                            <ig:EditingColumnSetting ColumnKey="CurrentDayMeterReading" EditorID="MachineID" />
                                                            </ColumnSettings>
                                                            </ig:CellEditing>
                                                            <ig:RowAdding>
                                                            </ig:RowAdding>
                                                        </Behaviors>

                                                    </ig:EditingCore>
                                                    <ig:RowSelectors>


                                                    </ig:RowSelectors>
                                                </Behaviors>




                                            </ig:WebDataGrid></pre>

protected void MeterReadingDataGrid_RowUpdating(object sender, Infragistics.Web.UI.GridControls.RowUpdatingEventArgs e)
   {



       int id;
       string machine = string.Empty;
       decimal lastDayReading = 0.0M;
       decimal currentDayReading = 0.0M;


       id = System.Convert.ToInt16(e.Values["MachineID"].ToString());
       machine = machine = e.Values["MachineDescription"].ToString();
       lastDayReading = System.Convert.ToDecimal(e.Values["LastDayMeterReading"].ToString());
       currentDayReading = System.Convert.ToDecimal(e.Values["CurrentDayMeterReading"].ToString());

       SqlConnection con = new SqlConnection(connectionString);
       SqlCommand cmd = new SqlCommand("EditDailyElectricityDetails", con);
       con.Open();
       cmd.CommandType = CommandType.StoredProcedure;
       cmd.Parameters.AddWithValue("id", id);
       cmd.Parameters.AddWithValue("lastdayreading", lastDayReading);
       cmd.Parameters.AddWithValue("currentdayreading", currentDayReading);
       cmd.ExecuteNonQuery();
       con.Close();
       DisplayGrid();


   }