[WebMethod]
    public int TestDBNullValue(string PID)
    {
        int ErrorValue = 0;
        if (PID.Equals(String.Empty))
        {
            ErrorValue = 10110; //PID is null or empty
        }
        else
        {
            DeviceTableAdapter DeviceAdapter = new DeviceTableAdapter();
            JeanPierre.DeviceDataTable DeviceTable = DeviceAdapter.GetDeviceUIDByPID(PID);

            if (DeviceTable.Count.Equals(0))
            {
                ErrorValue = 1111; //No device found
            }
            else
            {
                JeanPierre.DeviceRow DevRows = DeviceTable[0];

                if(DevRows.TrackingMode.Equals(System.DBNull.Value))
                {
                    ErrorValue = 1;
                }
                else
                {
                    ErrorValue = 41;
                }
            }
        }
        return (ErrorValue);
    }