Attach OnItemDataBound
event with your datalist like this
...
And define it like this
protected void Dlitems_ItemDataBound(Object sender, DataListItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Header)
{
Label lblCat = (Label)e.Item.FindControl("lblcat");
lblCat.Text = "Changed!";
}
}