为什么我不能让用户喜欢FB.api？

Question

当我检查是否有人喜欢我的页面时遇到了问题。我可以让大多数用户喜欢信息，但是使用api /me/likes/pageID，少数用户只返回类似"FB.__globalCallbacks.f2508bd33b46a1e({"data":[]});"的响应，数据为空。我在"https://developers.facebook.com/tools/explorer?method=GET&path=me%2Flikes"中调试了accessToken，它只返回相同的结果。

这是我的JavaScript代码。谁能告诉我我做错了什么？

        //use jquery init FB
        $.ajaxSetup({ cache: true });
    $.getScript('//connect.facebook.net/zh_HK/all.js', function(){
        // alert('初始化FACEBOOK，APPID是'+appId);
        FB.init({
            appId      : appId,                        // App ID from the app dashboard
            status     : true,                                 // Check Facebook Login status
            xfbml      : true,                               // Look for social plugins on the page
            cookie     : true,
            frictionlessRequests:true
        });

        var redirectURL=encodeURIComponent('https://apps.facebook.com/myapp?scope=offline_access,user_likes,email');
        // Additional initialization code such as adding Event Listeners goes here
        FB.getLoginStatus(function(response) {
            if (response.status === 'connected') {
                // the user is logged in and has authenticated your
                // app, and response.authResponse supplies
                // the user's ID, a~-0 valid access token, a signed
                // request, and the time the access token
                // and signed request each expire
                fbId = response.authResponse.userID;
                accessToken = response.authResponse.accessToken;
            } else if (response.status === 'not_authorized') {
                window.top.location.href = 'https://www.facebook.com/dialog/oauth?client_id=' + appId + '&redirect_uri='+redirectURL;
            } else {
                window.top.location.href = 'https://www.facebook.com/dialog/oauth?client_id=' + appId + '&redirect_uri=' +redirectURL
            }
        });

        FB.Event.subscribe('edge.create',
            function(response) {
                hideLayer('fb_like_box');
            });

    });

     //check fan or not
    FB.api('/me/likes/'+PageId, function (result) {
            if (result.data[0]) {
               alert('fan!')
            } else {
               alert('not fan!')  
                );
                return;
            }
        });