jQuery DataTables: How do I add a row ID to each dynamically added row?

Summary

I am using the great dataTables jQuery plugin from http://www.datatables.net. In my script, I am dynamically adding rows based on an event firing using fnAddData. Using fnRowCallback, I add in a unique row ID. This sometimes fails and does not add a row ID. In a test of 46 row additions, usually 6 to 8 rows do not get a row ID.

Add Row function

function ps_ins(row)
{
  var rowArray = row.split('|');
  row = rowArray;
  var alarmID = parseInt(row[1],10);

  $('#mimicTable').dataTable().fnAddData([
    alarmID, 'col2', 'col3', 'col4',
    'col5', 'col6', 'col7'
  ]);
}

Rows are added to the table correctly. The test I am running adds 46 rows, and all appear as expected.

Add the row ID

I am trying to add a unique ID to each row so I can later modify a specific row and refer to it in dataTable's cache using a combination of fnGetRows and .filter.

I am doing this using fnRowCallback during the initialisation stage. I've kept all the other settings just incase there's anything there that might have an impact on the problem.

  $('#mimicTable').dataTable({
    "sDom": 'lip<"mimicSpacer">f<"numUnAck">rt',
    "sScrollY": "365px",
    "aaSorting": [[4,'desc'],[5,'desc']],
    "iDisplayLength": 15,
    "aLengthMenu": [[15, 50, 100, -1], [15, 50, 100, 'All']],
    "bAutoWidth": false,
    "aoColumns": [
      null,
      { "sWidth": "20%" },
      { "sWidth": "22%" },
      { "sWidth": "9%" },
      { "sWidth": "9%" },
      { "sWidth": "20%" },
      { "sWidth": "20%" }
    ],
    "fnRowCallback": function( nRow, aData, iDisplayIndex, iDisplayIndexFull) {
      $(nRow).attr("id",'alarmNum' + aData[0]);
      return nRow;
    }
  });

A console.log of the dataTable object shows: