How to sort multiple datatables by field that have select inside?

ipechepare

Hi guys!
I can´t share a Url because the website is private of my company.
I try to explain my problem. I have multiple data tables generate like this:

comparables_table_list = $('#comparables-table-list').DataTable({
        paging: false,
        info: false,
        "sDom": '<"top"i>rt<"bottom"l><"clear">',
        "order": [[8, "asc"]],
        "aoColumns": [
            { "bSortable": false },
            null,
            null,
            null,
            null,
            null,
            {"sType": "numeric"},
            null,
            {"sType": "numeric"},
            {"sType": "numeric"},
            { "orderDataType": "dom-select" }
        ]
    });
    $.each(COMPS_TYPES, function( index, value ) {
        var type = value.SUB_TYPE;
        comparables_table_list_land[type] = $('[data-type="'+type+'"]').DataTable({
            paging: false,
            info: false,
            "sDom": '<"top"i>rt<"bottom"l><"clear">',
            "order": [[8, "asc"]],
            "aoColumns": [
                null,
                null,
                null,
                null,
                null,
                {"sType": "numeric"},
                null,
                {"sType": "numeric"},
                {"sType": "numeric"},
                { "orderDataType": "dom-select" }
            ]
        });
    });

And I use that to sort by field that have a select inside:

$.fn.dataTable.ext.order['dom-select'] = function  ( settings, col )
{
    return this.api().column( col, {order:'index'} ).nodes().map( function ( td, i ) {
        return $('select', td).val();
    } );
};

But when I try to sort by this field I can't If I have only a table them all work well.
Sorry form my poor english and I wait for yours answers, thanks!!