.Selected property doesn't get rendered in

Hi,

I want to fill a multi-select <asp:ListBox>. The data(<asp:ListItem>'s) will be provided by a LINQDatasource.

When I use a <asp:ListBox> the selected property of a <asp:ListItem> doesn't work, or at least doesn't get rendered.

When I use a <asp:Repeater> with the same datasource, the <asp:ListItem>'s do have a correct 'selected' value and the <asp:ListItem>'s do get initially selected when they are supposed to.

I want to use the <asp:ListBox>, why doesn't the <asp:ListItem>.Selected property get rendered.
 1 protected void lnqRoles_Selecting(object sender, LinqDataSourceSelectEventArgs e)
2 {
3 XDocument newsXML = XDocument.Load(Server.MapPath("~/App_Data/rollen.xml" ...