asp.net time lag

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
 
 
public partial class _Default: System.Web.UI.Page
{
    protected void Page_Load (object sender, EventArgs e)
    {
        if (! IsPostBack)
        {
            string connStr = "Server = .; Database = Test; uid = sa";
            SqlConnection conn = new SqlConnection (connStr);
            SqlCommand comm = new SqlCommand ("select NowDt from Table1 where DtId = 1", conn);
            System.DateTime aa; // Time stored in the database
            System.DateTime bb; // Current time
 
            // take the time in the database, the field is of type varChar
            try
            {
                conn.Open ();
                aa = Convert.ToDateTime (comm.ExecuteScalar (). ToString ()); // Database time, convert object to string and convert to DateTime
                conn.Close ();
            }
            catch (Exception exp)
            {
                throw exp;
            }
            finally
            {
                conn.Dispose ();
                comm.Dispose ();
            }
            this.HLOldDt.Text = aa.ToString (); // Time in database
 
            bb = System.DateTime.Now; // Current time
            this.HLNowDt.Text = bb.ToString (); // output the current time
 
            //jet lag  
            string ss = this.DateDiff (aa, bb);
            this.HLSe.Text = ss.ToString (); // output time difference
        }
    }
 
    // Compared time difference
    private string DateDiff (DateTime DateTime1, DateTime DateTime2)
    {
        string dateDiff = null;
          
        try
        {
            TimeSpan ts1 = new TimeSpan (DateTime1.Ticks);
            TimeSpan ts2 = new TimeSpan (DateTime2.Ticks);
            TimeSpan ts = ts1.Subtract (ts2) .Duration (); // Find the absolute value of the time difference
 
            // Build time string
            dateDiff = ts.Days.ToString () + "day" + ts.Hours.ToString () + "hour" + ts.Minutes.ToString () + "minute" + ts.Seconds.ToString () + "second";
        }
        catch
        {
        } return dateDiff;
    }
}