DALIComm - Instance of SerialportDALIDataGrid - Instance of Datagrid private void DALIComm_DataReceived(object sender, SerialDataReceivedEventArgs e) { // Process received data byte[] buffer = new byte[2];//DALIComm.BytesToRead]; int bytesRead = DALIComm.Read(buffer, 0, buffer.Length); strNewRowData[4] = Convert.ToBase64String(buffer); bUpdateDataGrid = true; AddNewRow(); } public void AddNewRow() { if(bUpdateDataGrid) { DateTime TempData; long DeltaTime; gu32SerialNumber++; strNewRowData[0] = gu32SerialNumber.ToString(); strNewRowData[1] = System.DateTime.Now.ToShortDateString(); TempData = System.DateTime.Now; TimeSpan span = TempData.Subtract(Convert.ToDateTime(strNewRowData[2])); DeltaTime = (long)span.TotalMilliseconds; strNewRowData[3] = Convert.ToString(DeltaTime); strNewRowData[2] = TempData.ToString("hh:mm:ss.fff tt"); strNewRowData[5] = "1"; DALIDataGrid.Rows.Add(strNewRowData); bUpdateDataGrid = false; } }Error on the line which is highlighted in bold and size-4.