Bulk Insert into Access Database not working for template fields in gridview

protected void Button1_Click(object sender, EventArgs e)
   {
       foreach (GridViewRow gvrow in GridView1.Rows)
       {
            string sid = gvrow.Cells[0].Text;
           RadioButtonList rbAtt = (RadioButtonList)GridView1.Rows[selectedIndex].FindControl("rbAtt");
           con.Open();
           SqlCommand cmd = new SqlCommand("InsertAttendence", con);
           cmd.CommandType = CommandType.StoredProcedure;
           cmd.Parameters.AddWithValue("@StudentId", sid);
           if (dlAtt.SelectedItem.Text=="Morning")
           {
               cmd.Parameters.AddWithValue("@Morning", rbAtt.SelectedValue);
           }
           else
           {
               cmd.Parameters.AddWithValue("@Morning", DBNull.Value);
           }
           if (dlAtt.SelectedItem.Text=="Evening")
           {
               cmd.Parameters.AddWithValue("@Evening", rbAtt.SelectedValue);
           }
           else
           {
               cmd.Parameters.AddWithValue("@Evening", DBNull.Value);
           }

           cmd.ExecuteNonQuery();
           con.Close();
       }

   }