private void ComboDocNo_TextChanged(object sender, EventArgs e)
 {
     FormatBtnUpdate();
     FormatBtnDelete();
     // Loading data into the form:
     try
     {
         using (DBAuditDataContext dc = new DBAuditDataContext())
         {
             if (ComboDocNo.Text != "")
             {
                 string   StrDocNo      = null;
                 DateTime?VarDatePay    = null;
                 int?     IntLocationID = null;
                 int?     IntEmployeeID = null;
                 string   StrLocation   = null;
                 string   StrEmployee   = null;
                 string   StrPerson     = null;
                 decimal? decimalAmount = null;
                 string   StrDesc       = null;
                 string   StrNotes      = null;
                 var      c             = dc.ProSelectCure(ComboDocNo.Text, ref StrDocNo, ref IntEmployeeID, ref IntLocationID, ref StrPerson, ref decimalAmount, ref VarDatePay, ref StrDesc, ref StrNotes);
                 TxtDocNo.Text = StrDocNo;
                 if (VarDatePay != null)
                 {
                     DatePayDate.Value = VarDatePay.Value;
                 }
                 var d = dc.ProGetLocationByID(IntLocationID, ref StrLocation);
                 ComboLocation.Text = StrLocation;
                 var x = dc.ProGetEmployeeByID(IntEmployeeID, ref StrEmployee);
                 ComboName.Text = StrEmployee;
                 TxtPerson.Text = StrPerson;
                 TxtAmount.Text = decimalAmount.ToString();
                 TxtDesc.Text   = StrDesc;
                 TxtNotes.Text  = StrNotes;
             }
             else
             {
                 TxtDocNo.Text      = "";
                 TxtPerson.Text     = "";
                 ComboLocation.Text = "";
                 TxtAmount.Text     = "";
                 TxtDesc.Text       = "";
                 TxtNotes.Text      = "";
             }
         }
     }
     catch (NullReferenceException)
     {
         BtnDelete.Enabled = false;
     }
     catch (InvalidOperationException)
     {
         BtnDelete.Enabled = false;
     }
     catch (Exception EX)
     {
         MessageBox.Show(EX.Message);
     }
 }