Check All and Uncheck all

[Hemanth]

Hi,
Here i have Telerik Rad Grid, i need check all and Uncheck all functions need to be done
Here is my code...

     <telerik:GridViewDataColumn Width="30">
                    <telerik:GridViewColumn.Header>
                        <CheckBox  Name="chkall" Checked="CheckBox_Checked" Unchecked="CheckBox_Unchecked">
                        </CheckBox>
                    </telerik:GridViewColumn.Header>
                    <telerik:GridViewColumn.CellTemplate>
                        <DataTemplate>
                            <CheckBox Name="chk" CommandParameter="{Binding ID}">
                            </CheckBox>
                        </DataTemplate>
                    </telerik:GridViewColumn.CellTemplate>
                </telerik:GridViewDataColumn>


for CheckBox_Checked and CheckBox_Unchecked in .cs page
what i need to code

Thanks