Grid Check box

protected void Button1_Click(object sender, EventArgs e)
{
Label lb1 = new Label();
CheckBox chk1 = new CheckBox();
foreach (GridViewRow grd in GridView1.Rows)
{
chk1 = (CheckBox)grd.FindControl("CheckBox1");
if (chk1.Checked == true)
{
lb1 = (Label)grd.FindControl("Label1");
}
TextBox1.Text = lb1.Text.ToString();
}
}