I add this javascript code to select date and time.But it doesn't work. Can anybody help me? 

```
<div class="input-append date form_datetime">
        <input size="16" type="text" value="" readonly>
        <span class="add-on"><i class="icon-th"></i></span>
    </div>

    <script type="text/javascript">
        $(".form_datetime").datetimepicker({
            format: "dd MM yyyy - hh:ii",
            autoclose: true,
            todayBtn: true,
            pickerPosition: "bottom-left"
        });
    </script>            

```