How to: get array of first column where checkbox is checked in datatables

Putjes

I need the values of the first column in my datatables. This methode does not work very good... this in oTable.fnGetPosition(this); returns the button and not the checkbox. How to create a method that returns all the values of the first column where the checkbox (in 5th column ) is checked.

    $('#saveChangesButton').click(function () {
        var dataArr = [];
        $("input:checked", oTable.fnGetNodes()).each(function () {
            var position = oTable.fnGetPosition(this); // getting the clicked row position
            var id = oTable.fnGetData(position)[0]; // getting the value of the first (invisible) column
            dataArr.push(id);
            alert(dataArr);
        });
        $('#guidsToBlock').val(dataArr);
    });

thanks in advance...
R.