TableTools with row grouping

pix

hello
I can not put up with the tableTools grouping column.
printing works but not export in csv or pdf.
The first column is printed on top of next column
thank you for your help
[code]
oTable = $('#example').dataTable({
'sDom': 'T<"clear"><"H"frl>t<"F"ip>',
'oTableTools': {
'sSwfPath': 'media/copy_cvs_xls_pdf.swf',
'aButtons': [ { 'sExtends': 'csv', 'sButtonText': 'Exporter en CSV' },
{ 'sExtends': 'pdf', 'sButtonText': 'Exporter en PDF' },
{ 'sExtends': 'print', 'sButtonText': 'Imprimer' } ]
},
"fnDrawCallback": function ( oSettings ) {
if ( oSettings.aiDisplay.length == 0 ){
return;
}

var nTrs = $('#example tbody tr');
var iColspan = nTrs[0].getElementsByTagName('td').length;
var sLastGroup = "";
for ( var i=0 ; i