Page length options / lengthMenu doesn't show up

Hi all,

My DataTables is working correctly, however the Page length options / lengtMenu isn't show up anymore. I wonder what could be the reason?

My config:

$('#debiteurdata').DataTable( {
        "order": [[ 0, "desc" ]],
        "lengthMenu": [[10, 25, 50, -1], [10, 25, 50, "All"]],
        "bPaginate": true,
        "lengthChange": true,
        "iDisplayLength": 25,
        "language": {
            "sProcessing": "Bezig...",
            "sLengthMenu": "_MENU_ resultaten weergeven",
            "sZeroRecords": "Geen resultaten gevonden",
            "sInfo": "_START_ tot _END_ van _TOTAL_ resultaten",
            "sInfoEmpty": "Geen resultaten om weer te geven",
            "sInfoFiltered": " (gefilterd uit _MAX_ resultaten)",
            "sInfoPostFix": "",
            "sSearch": "Zoeken:",
            "sEmptyTable": "Geen resultaten aanwezig in de tabel",
            "sInfoThousands": ".",
            "sLoadingRecords": "Een moment geduld aub - bezig met laden...",
            "oPaginate": {
            "sFirst": "Eerste",
            "sLast": "Laatste",
            "sNext": "Volgende",
            "sPrevious": "Vorige"
            }
        },
        dom: 'T<"clear">lfrtip',
        tableTools: {
            "sSwfPath": "js/copy_csv_xls_pdf.swf"
        },
        
        "fnDrawCallback": function( oSettings ) {
         $(".cbShowOrHideGvCols").appendTo("div.dataTables_length");
        }


    } );

Thanks for any help.