DataList控件绑定后为什么不显示？

Question

public partial class index : System.Web.UI.Page
{
SqlConnection con = null;
SqlCommand cmd = null;
SqlDataAdapter datp = null;
DataSet ds = new DataSet();
string constr = "";
protected void Page_Load(object sender, EventArgs e)
{
UnobtrusiveValidationMode = UnobtrusiveValidationMode.None;
this.DataList1.DataSource = getDataTable("select top 3 * from ContentText");
this.DataList1.DataBind();
}
public DataTable getDataTable(string sql)
{
constr = System.Configuration.ConfigurationManager.ConnectionStrings["constr"].ToString();
try
{
con = new SqlConnection(constr);
con.Open();
//Response.Write("ok");
cmd = new SqlCommand(sql, con);
datp = new SqlDataAdapter(cmd);
datp.Fill(ds);
}
catch (Exception e1)
{
System.Diagnostics.Debug.WriteLine(e1.Message);
}
finally
{
con.Close();
}
return ds.Tables[0];
}

    数据库连接成功的，sql语句也没毛病