RadGRID Checkbox

protected void CheckBox1_CheckedChanged(object sender, EventArgs e)
{
CheckBox chkbx = (CheckBox)sender;
Label list = (Label)((chkbx.NamingContainer).FindControl("Label1"));
string text = list.Text;
bool chkSatus = chkbx.Checked;

if ((sender as CheckBox).Checked)
{
foreach (GridDataItem dataItem in RadGrid1.MasterTableView.Items)
{
(dataItem.FindControl("CheckBox1") as CheckBox).Checked = true;
dataItem.Selected = true;
}
}
else
{
foreach (GridDataItem dataItem in RadGrid1.MasterTableView.Items)
{
(dataItem.FindControl("CheckBox1") as CheckBox).Checked = false;
dataItem.Selected = false;
}
}
}