protected void DataList1_ItemDataBound(object sender, DataListItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Footer)
        {
            if (e.Item.FindControl("Label1") != null)
            {
                Label lbl = (Label)e.Item.FindControl("Label1");
            }
        }
    }

------解决方案--------------------
 protected void DataList1_ItemDataBound(object sender, DataListItemEventArgs e)
   {
       if (e.Item.ItemType == ListItemType.Footer)
       {
           if (e.Item.FindControl("Label1") != null)
           {
               Label lbl = (Label)e.Item.FindControl("Label1");
           }
       }
   }