AJAX返回的页码不能执行函数？？？

如果直接在页面中写代码

<div class="mui-content-padded" id="pagesitem1">
<ul class="mui-pager">
<li class="mui-previous mui-disabled"><a href="#">&laquo;</a></li>
<li class="mui-active"><a href="#">1</a></li>
<li><a href="#">2</a></li>
<li><a href="#">3</a></li>
<li><a href="#">4</a></li>
<li><a href="#">5</a></li>
<li class="mui-next"><a href="#">&raquo;</a></li>
</ul>
</div>

脚本：
$('#pagesitem1').on('tap', 'a', function(e) {
var page = this.innerText;
ajaxitem1(page);
});

var ajaxitem1 = function(p) {
var url = '地址';
var type = 'post';
var dataType = 'json';
var data = {
page:p
};
$.post(url, data, successitem1, dataType);

    };   
    //成功响应的回调函数  
    var successitem1 = function(data) {  
        //data = JSON.stringify(data);//转化为字符串            
        //alert(data);  
        item1.innerHTML='';           
        for(var i=0;i<data.content.length;i++){  
            item1.innerHTML +="<li class=\"mui-table-view-cell mui-media mui-col-xs-6\"><a href=\"#\"><img class=\"mui-media-object\" src=\""+data.content[i].titlepic+"\"/><div class=\"mui-media-body\">"+data.content[i].title+"</div></a></li>";  
        }   
        item1.innerHTMLtop ="<ul class=\"mui-table-view mui-grid-view\">";  
        item1.innerHTMLbot ="</ul>";  
        item1.innerHTMLpage =data.page;  
        item1.innerHTML=item1.innerHTMLtop+item1.innerHTML+item1.innerHTMLbot+item1.innerHTMLpage;  
        //alert(item1.innerHTML);  

    };  

可以执行函数

返回的代码有page参数：内容也是
<div class="mui-content-padded" id="pagesitem1">
<ul class="mui-pager">
<li class="mui-previous mui-disabled"><a href="#">&laquo;</a></li>
<li class="mui-active"><a href="#">1</a></li>
<li><a href="#">2</a></li>
<li><a href="#">3</a></li>
<li><a href="#">4</a></li>
<li><a href="#">5</a></li>
<li class="mui-next"><a href="#">&raquo;</a></li>
</ul>
</div>
但是点击没效果？这是为何？？