Label Showing User.identity.name In Detailsview

Hi, any suggestions on why my label doesn't show the current user.identity.name when used in a detailsview (header-field or insert-field), when it works just fine placed directly on my page ?

Please help ! (I want to bind myLabelX.Text to a db-table, but it contains no value..)

codebehind  : 1 using System;
2 using System.Data;
3 using System.Configuration;
4 using System.Collections;
5 using System.Web;
6 using System.Web.Security;
7 using System.Web.UI;
8 using System.Web.UI.WebControls;
9 using System.Web.UI.WebControls.WebParts;
10 using System.Web.UI.HtmlControls;
11
12
13 public partial class Test_2 : System.Web.UI.Page
14 {
15
16 protected void Page_Load(object sender, EventArgs e)
17 {
18 if ((!IsPostBack)) myLabelX.Text = User.Identity.Name;
19 }
20
21 }