Value gets diappeared when I press Tab

[raghul]

Hi,
When ever I press tab the values present in the celledittemplate column gets disappeared. Please find the attached coding, Please let me know where I am going wrong. In the below coding the numericupdown control value gets disappeared after tab is pressed from the last cell of the row.

<telerik:RadGridView x:Name="grdStatus" telerik:StyleManager.Theme="Summer" ShowGroupPanel="False" CanUserDeleteRows="False"
                                 AutoExpandGroups="False" AutoGenerateColumns="False" RowIndicatorVisibility="Collapsed"  Grid.Row="2"
                                 HorizontalAlignment="Left" BorderBrush="Black" Height="Auto" ShowInsertRow="True"
                                 ScrollViewer.VerticalScrollBarVisibility="Auto" IsFilteringAllowed="True" Margin="5,10,5,0" Visibility="Collapsed"
                                 ScrollViewer.HorizontalScrollBarVisibility="Auto" RowEditEnded="grdStatus_RowEditEnded">
                        <telerik:RadGridView.Columns>
                            <telerik:GridViewComboBoxColumn Width="*" Header="Status"  DataMemberBinding="{Binding StatusId}" DisplayMemberPath="StatusName" SelectedValueMemberPath="Id" UniqueName="StatusColumn" IsVisible="True"/>
                            <telerik:GridViewComboBoxColumn Width="*" Header="Order"  DataMemberBinding="{Binding OrderId}" UniqueName="OrderColumn" DisplayMemberPath="OrderName" SelectedValueMemberPath="Id" IsVisible="True" IsReadOnly="False"/>
                            <telerik:GridViewColumn Width="*">
                                <telerik:GridViewColumn.Header>
                                    <Grid>
                                        <Grid.RowDefinitions>
                                            <RowDefinition></RowDefinition>
                                            <RowDefinition></RowDefinition>
                                        </Grid.RowDefinitions>
                                        <Grid.ColumnDefinitions>
                                            <ColumnDefinition></ColumnDefinition>
                                            <ColumnDefinition></ColumnDefinition>
                                            <ColumnDefinition></ColumnDefinition>
                                        </Grid.ColumnDefinitions>
                                        <TextBlock Text="Escalate by" Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="3" HorizontalAlignment="Center"></TextBlock>
                                        <TextBlock Text="Days" Grid.Column="0" Grid.Row="1" TextAlignment="Center" Width="75"></TextBlock>
                                        <TextBlock Text="Hours" Grid.Column="1" Grid.Row="1" TextAlignment="Center" Width="75"></TextBlock>
                                        <TextBlock Text="Minutes" Grid.Column="2" Grid.Row="1" TextAlignment="Center" Width="75"></TextBlock>
                                    </Grid>
                                </telerik:GridViewColumn.Header>
                                <telerik:GridViewColumn.CellTemplate>
                                    <DataTemplate>
                                        <Grid>
                                            <Grid.ColumnDefinitions>
                                                <ColumnDefinition></ColumnDefinition>
                                                <ColumnDefinition></ColumnDefinition>
                                                <ColumnDefinition></ColumnDefinition>
                                            </Grid.ColumnDefinitions>
                                            <telerik:RadNumericUpDown x:Name="tbStDays"  Grid.Column="0"  IsEditable="False" Width="Auto" telerik:StyleManager.Theme="Windows7" Minimum="0" Maximum="31" NumberDecimalDigits="0" Value="{Binding TimeDays}"></telerik:RadNumericUpDown>
                                            <telerik:RadNumericUpDown x:Name="tbStHrs"  Grid.Column="1"  IsEditable="False" Width="Auto" telerik:StyleManager.Theme="Windows7" Minimum="0" Maximum="59" NumberDecimalDigits="0" Value="{Binding TimeHours}"></telerik:RadNumericUpDown>
                                            <telerik:RadNumericUpDown x:Name="tbStMin"  Grid.Column="2"  IsEditable="False" Width="Auto" telerik:StyleManager.Theme="Windows7" Minimum="0" Maximum="59" NumberDecimalDigits="0" Value="{Binding TimeMinutes}"></telerik:RadNumericUpDown>
                                        </Grid>
                                    </DataTemplate>
                                </telerik:GridViewColumn.CellTemplate>
                                <telerik:GridViewColumn.CellEditTemplate>
                                    <DataTemplate>
                                        <Grid>
                                            <Grid.ColumnDefinitions>
                                                <ColumnDefinition></ColumnDefinition>
                                                <ColumnDefinition></ColumnDefinition>
                                                <ColumnDefinition></ColumnDefinition>
                                            </Grid.ColumnDefinitions>
                                            <telerik:RadNumericUpDown x:Name="tbsDays" IsEditable="True"  Grid.Column="0"  Width="Auto" telerik:StyleManager.Theme="Windows7" Minimum="0" Maximum="31" NumberDecimalDigits="0" Value="{Binding TimeDays}"></telerik:RadNumericUpDown>
                                            <telerik:RadNumericUpDown x:Name="tbsHrs" IsEditable="True"  Grid.Column="1"  Width="Auto" telerik:StyleManager.Theme="Windows7" Minimum="0" Maximum="59" NumberDecimalDigits="0" Value="{Binding TimeHours}"></telerik:RadNumericUpDown>
                                            <telerik:RadNumericUpDown x:Name="tbsMin" IsEditable="True" Width="Auto"  Grid.Column="2"  telerik:StyleManager.Theme="Windows7" Minimum="0" Maximum="59" NumberDecimalDigits="0" Value="{Binding TimeMinutes}"></telerik:RadNumericUpDown>
                                        </Grid>
                                    </DataTemplate>
                                </telerik:GridViewColumn.CellEditTemplate>
                            </telerik:GridViewColumn>
                            <telerik:GridViewColumn Width="*" Header="Is Escalation Required">
                                <telerik:GridViewColumn.CellTemplate>
                                    <DataTemplate>
                                        <StackPanel Orientation="Horizontal">
                                            <RadioButton Name="RadioYes" GroupName="{Binding GroupName}" Content="Yes" IsChecked="{Binding RadioYes}"></RadioButton>
                                            <RadioButton Name="RadioNo" GroupName="{Binding GroupName}" Content="No" IsChecked="{Binding RadioNo}"></RadioButton>
                                        </StackPanel>
                                    </DataTemplate>
                                </telerik:GridViewColumn.CellTemplate>
                                <telerik:GridViewColumn.CellEditTemplate>
                                    <DataTemplate>
                                        <StackPanel Orientation="Horizontal">
                                            <RadioButton Name="RadioYes" GroupName="UserAcceptence" Content="Yes" IsChecked="{Binding RadioYes}"></RadioButton>
                                            <RadioButton Name="RadioNo" GroupName="UserAcceptence" Content="No" IsChecked="{Binding RadioNo}"></RadioButton>
                                        </StackPanel>
                                    </DataTemplate>
                                </telerik:GridViewColumn.CellEditTemplate>
                            </telerik:GridViewColumn>
                            <telerik:GridViewDataColumn Width="*" Header="Escalate To"  DataMemberBinding="{Binding EscalateTo}" UniqueName="EscToColumn" IsVisible="True" IsReadOnly="False"/>
                        </telerik:RadGridView.Columns>
                    </telerik:RadGridView>