jquery dataTables and bootstrap btn-group dropdown

I've a view problem using bootstrap buttons group dropdown inside a jquery datatables plugin (datatables.net). See pic: [IMG]http://i66.tinypic.com/5x4d1v.jpg[/IMG]

My table has this options sets:

$('#tabellaContatti').dataTable( {
    "language": {
        "url": "../../assets/advanced-datatable/Languages/Italian.json"
    "aaSorting": [[ 0, "asc" ]],
    responsive: true,
    paging: true,
    "pageLength": 5,
    "lengthMenu": [ [5, 10, 15, -1], [5, 10, 15, "Tutti"] ],
    "info": false,
    scrollCollapse: false,
    scrollY: false,
    "columnDefs": [
        { "orderable": false, "targets": 4 }

No scrolling Y is present! Now if I click the dropdown button "AZIONI" in the last row, scrolling appears and menu appears cutted... Is there a way to prevent the scrolling appear? I believe Z-INDEX help me without success....