cross domain ajax works but there's no data displayed in my table : (

https://datatables.net/release-datatables/examples/server_side/jsonp.html

The above setting works (below) - confirmed on the firebug, the JSON data is retrieved, but my issue is it's not shown on the table!!

Any clues why??

    $(document).ready(function() {
        $('#table_id').dataTable( {
                "bProcessing": true,
                "bServerSide": true,
				"sAjaxSource": "http://localhost:9001/api/gui/messages",
				"fnServerData": function( sUrl, aoData, fnCallback, oSettings ) {
			            oSettings.jqXHR = $.ajax( {
			                "url": sUrl,
			                "data": aoData,
			                "success": fnCallback,
			                "dataType": "jsonp",
			                "cache": false
			            } );
				},
                "bDeferRender": true,
                "aoColumns": [
						{ "mData": "busId", "bSortable": false },
						{ "mData": "sourceSystem", "bSortable": false },
						{ "mData": "receiveTime", "bSortable": false },
                                                ...
				     ],
                "sDom": "rtp",
                "sPaginationType": "full_numbers",
                "iDisplayLength": 20
            } );
        } );               

Just to verify things, if source data locally i.e. replace:
"sAjaxSource": "http://localhost:9001/api/gui/messages",
"fnServerData" ...

with something like:
"sAjaxSource": "resources/data.txt",

then all works!

I'm using DataTables 1.9.4

Thanks!