read value from one gridview to another gridview but checkbox value cant pass in coding...

protected void btnget_Click(object sender, EventArgs e)
        {
            foreach (GridViewRow row in GridView1.Rows)
            {
                CheckBox ChkData = (CheckBox)row.FindControl("chkSelect");
                if (ChkData.Checked == true)
                {
                    string firstname = Convert.ToString(((Label)row.FindControl("labelfirstname")).Text);
                    string lastname = Convert.ToString(((Label)row.FindControl("labellastname")).Text);
                    string email = Convert.ToString(((Label)row.FindControl("email")).Text);
                    string reemail = Convert.ToString(((Label)row.FindControl("reemail")).Text);
                    string newpassword = Convert.ToString(((Label)row.FindControl("newpassword")).Text);
                    string birthday = Convert.ToString(((Label)row.FindControl("birthday")).Text);
                    string gender = Convert.ToString(((Label)row.FindControl("gender")).Text);
                }