C#.Net Login failed for user ''. Hatası

    protected override **** OnStart(string[] args) 
    { 
      try 
      { 
        firstControlTimer.Start(); 
        durationTrueFrequencyTrueTimer.Start(); 
        durationFalseFrequencyTrueTimer.Start(); 
        durationTrueFrequencyFalseTimer.Start(); 
        durationFalseFrequencyFalseTimer.Start(); 
        durationFalseFrequencyTrueControl(); 
        //durationTrueFrequenctTrueControl(); 
        //durationFalseFrequencyFalseControl(); 
        //durationTrueFrequencyFalseControl(); 
      } 
      catch (Exception ex) 
      { 
        StreamWriter sw = new StreamWriter(@"D:\hata.txt"); 
        sw.WriteLine(ex.Message); 
        sw.Close(); 
      } 
    }

    public **** durationFalseFrequencyTrueControl() 
    { 
        string sorgu = "select RECORD.LREF FROM RECORD,TIME where RECORD.ACTIVE='True' and TIME.DURATION='False' and FREQUENCY='True' and TIME.START_DATE < GETDATE() and RECORD.LREF = TIME.LREF"; 
        SqlDataAdapter adap = new SqlDataAdapter(sorgu, con); 
        DataTable dt = new DataTable(); 
        con.Open(); 
        adap.Fill(dt); 
        con.Close(); 

        if (dt.Rows.Count > 0) 
        { 
          for (int i = 0; i < dt.Rows.Count; i++) 
          { 
            GlobalVariables.durationFalseFrequencyTrueJobs = dt.Rows["LREF"].ToString(); 
          } 
          GlobalVariables.durationFalseFrequencyTrueJobs = new string[dt.Rows.Count]; 
        } 
    }