Bootstrap selectpicker，标签输入后没有换行

Question

我遇到了selectpicker的问题。当我使用它时，输入不包裹。

例如：

 <div class="form-group col-sm-6">
 <label for="sesso">Sesso dei partecipanti</label>
 <select class="selectpicker" data-live-search="true" name="sesso" id="sesso">
 <option value="" disabled="" selected="selected" class="hide-option">Seleziona</option>
<option value="M">Maschile</option>
 <option value="F">Femminile</option>
<option value="X">Misto</option>
</select>                            
</div>

标签标签后没有selectpicker输入换行：

<div class="form-group col-sm-6">
<label for="numero_partecipanti">Numero Partecipanti</label>
 <input type="text" class="form-control" name="numero_partecipanti" id="numero_partecipanti">
</div>

这是带有完整html的网址： http://www.mytennishouse.com/home/test.php