Ajax在服务器上不工作，但在本地主机上工作得很好

Ajax调用无法在整个站点中工作。但在localhost中工作良好。我无法调试这个问题。

我已经使用ajax整个网站。我完全受够了。

我的一个示例Ajax代码:

function advanced_addTopic(cid) {    
  $.ajax({
        url: "assets/php/checkSubtopicStatus.php", // Url to which the request is send
        type: "POST",             // Type of request to be send, called as method
        data: {'cid':cid}, // Data sent to server, a set of key/value pairs (i.e. form fields 
        success: function(data)   // A function to be called if request succeeds
        {
              if(data==="True"){
                $("#subtopicDiv").html($("#subtopicDiv"+cid).html());
                $("#advanced_testid").val(cid);
                var hiddenCourse=$("#createTest").attr('class');
                $("#courseHidden").val(hiddenCourse);
                $("#advanced_addquestionModal").modal('show');
                $("#subtopic").focus();
                $("#question").focus();
                var tempVal=$("#getID").text(); 
                $("#advanced_courseHidden").val(cid);
                } else {
                  alert("Create subtopics to insert questions!");
                }
        }
 });

我的PHP代码在这里:

<?php 
        class loginValidation {  
             function validate() 
             {
                ob_start();
                session_start();
                include "../../connection.php"; 
                $id=$_POST['cid'];
                $query = mysql_query("select * from advanced_subtopic where testid='$id'");
                if(mysql_num_rows($query)>0) {
                        echo "True";    
                 } 
                else {
                        echo "False";
                }
            }
        }
        $loginValidation=new loginValidation;
        $loginValidation->validate();?>

My console Log

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