help for add extra col with tag html by sAjaxSource

hello boys, i have a problem for add extra col, i have tried a lot of examples:
http://www.datatables.net/blog/Drill-down_rows
http://www.datatables.net/release-datatables/examples/api/row_details.html
...
but it don't work
the error is:
DataTables warning (table id = 'datatable'): Requested unknown parameter 'browser' from the data source for row 0

my code is:

          "bProcessing": true,
          "bServerSide": true,
          "sAjaxSource": "server_processing.php",
          "aoColumns" : [ {
                                                "mData" : "browser",
                                                "bSearchable" : false,
                                                "bVisible" : false
                                            }, {
                                                "mData" : "platform",
                                                "bSearchable" : false,
                                                "bVisible" : false
                                            }, {
                                                "mData" : "version"
                                            }, {
                                                "mData" : "grade",
                                                "bSearchable" : false,
                                                "bVisible" : false
                                                
                                            },  {
                                                "mData" : null,
                                                "bSearchable" : false,
                                                "bSortable" : false,
                                                "fnRender" : function(oObj) {
                                                    return '<a class=""><img src="css/datatable/images/details_open.png" alt="Edit" />';
                                                }
                                }]   

html code:

<thead>
		<tr> 
			<th>Browser</th>
			<th>Platform(s)</th>
			<th>version</th>
			<th>grade</th>
                        <th style="width: 20px;"> </th>
		</tr>
	</thead>
	<tbody>
		<tr>
			<td colspan="5" class="dataTables_empty">Loading data from server</td>
		</tr>
	</tbody>

php array for query:

aColumns = array(  'browser', 'platform', 'version', 'grade');

at the end my debug:
http://debug.datatables.net/ibenuk

i spent more than 4 hours to fix it but nada, am i an idiot ? :)
and for now goodnight...
tnk for all.