asp.net中施用window.showModalDialog弹出窗口,为何第二次打开时不执行Page_Load

asp.net中使用window.showModalDialog弹出窗口,为何第二次打开时不执行Page_Load?
如题

------解决方案--------------------------------------------------------
去缓存，很简单啊
<meta http-equiv= "Expires " content= "0 ">
<meta http-equiv= "Cache-Control " content= "no-cache ">
<meta http-equiv= "Pragma " content= "no-cache ">