C# data reader does not retrieve the data
<p>I am trying to load data into a textbox by using a <code>DataReader</code> depend on the Drop down list selection. Didn't get error from this code, but the data is not loaded into textbox. please correct me.</p>

<pre><code>public void text()
{
    cn1.Open();
    string s;
    s = "select Request_Type from component where Material_Code='" + Mcodeddl.SelectedItem.Text + "' ";

    SqlCommand cd1 = new SqlCommand(s, cn1);
    SqlDataReader rd;

    try
    {
        rd = cd1.ExecuteReader();

        while (rd.Read())
        {
            TextBox4.Text = rd["Request_Type"].ToString().Trim();
        }

        rd.Close();
    }
    catch (Exception e)
    {
        Response.Write(e.Message);
    }
    finally
    {
        cd1.Dispose();
        cn1.Close();
    }
}

public void MC()
{
    Mcodeddl.Items.Clear();
    ListItem li1 = new ListItem();
    li1.Text = "-Select-";
    Mcodeddl.Items.Add(li1);
    Mcodeddl.SelectedIndex = 0;

    cn1.Open();
    string s1;
    s1 = "select Material_Code from component";

    SqlCommand cd1 = new SqlCommand(s1, cn1);
    SqlDataReader dr1;

    try
    {
        dr1 = cd1.ExecuteReader();

        while (dr1.Read())
        {
            ListItem ni1 = new ListItem();
            ni1.Text = dr1["Material_Code"].ToString().Trim();
            Mcodeddl.Items.Add(ni1);
        }

        dr1.Close();
    }
    catch (Exception e)
    {
        Response.Write(e.Message);
    }
    finally
    {
        cd1.Dispose();
        cn1.Close();
    }
 }
</code></pre>
