clearInterval 子页面中失效

有2个页面A和B,
A页面使用iframe包含B页面
测试如下:
A页面代码如下:
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title></title>
    <script src="../js/jquery.min.js" type="text/javascript"></script>
    <script src="../js/jquery.uploadify/jquery.uploadify.js" type="text/javascript"></script>
    <link href="../js/jquery.uploadify/uploadify.css" rel="stylesheet" type="text/css" />
    <script language="javascript" type="text/javascript">
        function test() {            window.frames["content"].autoRefresh1();
            return false;
        }        function test1() {            clearInterval(window.frames["content"].autotimer);
            return false;
        }    </script>
</head>
<body>
    <form id="form2" runat="server">
    <asp:Button ID="Button1" runat="server" Text="Button" OnClientClick="test();return false;" />
    <asp:Button ID="Button2" runat="server" Text="Button" OnClientClick="test1();return false;" />
    <iframe id='content' name="content" src="WebForm1.aspx" width="100%" height="100%">
    </iframe>
    </form>
</body>
</html>
B页面如下:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<script src="../js/jquery.min.js" type="text/javascript"></script>
<script type="text/javascript" language="javascript">
    var autotimer = null;
    function autoRefresh1() {
        autotimer = setInterval("myfunction()", 1000);
    }
    
    function myfunction() {
        $('#<%=Button1.ClientID %>').click();
    }
</script>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
            </ContentTemplate>
        </asp:UpdatePanel>
    </div>
    </form>
</body>
</html>
点击A页面Button1,启动B页面的setInterval方法,
启动后,点击A页面的Button2,通过js来停止B页面的autotimer ,但是不起作用啊js autotimer setInterval