firefox中的上传图片问题

    <div class="photo_add">
        <div class="btn_aa">
            <input id="File1" type="file" style="display: none;" name="file1" />
        </div>
        <input id="btnadd_photeo" type="button" value="添加相片" class="btn_add_photo" onclick="btnadd_photo_click()" />        <script type="text/javascript">  
           function btnadd_photo_click()
           {
               document.getElementById("form1").File1.click();
           }
        </script>        <div class="photo_all">
            <span class=" photos" id="sp1"></span><span class=" photos" id="sp2"></span><span
                class=" photos" id="sp3"></span><span class=" photos" id="sp4"></span><span class=" photos"
                    id="sp5"></span><span class=" photos" id="sp6"></span><span class=" photos" id="sp7">
                    </span><span class=" photos" id="sp8"></span><span class=" photos" id="sp9">
            </span><span class=" photos" id="sp10"></span><span class=" photos" id="sp11"></span>
            <span class=" photos" id="sp12"></span>
        </div>
    </div>     这段代码为在IE中有效果，在Firefox 中无效果 这是为什么？
     请知道帮我解决一下  
      急需答案
      ！！！！！！