$ .ajax成功未执行

I have in my .js file a function that call a webservices method called getStudents:

    [WebMethod(Description = "white student list")]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public List<Job> getStudents(long classId)
    {
        return (new classManager()).getStudents(classId);
    }

the method is callled like:

function loadStudents() {

    var parameters = JSON.stringify({ 'classId': 0 });

    alert(parameters);

    $("#ProcessingDiv").show('fast', function() {
        $.ajax({
            type: "POST",
            url: "myWebService.asmx/getStudents",
            data: parameters,
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function(response) {
                  $("#ProcessingDiv").hide();
                  var students= response.d;
                  alert('yes');
            },

            error: function(request, status, error) {
                alert(request.responseText);
            }
            ,
            failure: function(msg) {
                alert('somethin went wrong' + msg);
            }
        });
    });
}
$(document).ready(function() {

    loadStudents();
});

when i debug,the service web method is executed successfully but i don't get my alert('yes') and neither msg error.

What's wrong?

If you're returning (serialized to JSON) List of objects, then in response you will get JS array of JS objects, so (assuming Job has property p) try response[0].p for p value from first element.

note: I don't know ASP.NET, so maybe response is serialized in another way, thats where tools like Firebug (or other browsers Dev tools) are extremely useful - because you can look how exactly you'r http requests and responses looks like.

ps. And change alert to console.log and look for logs in Firebug console - its better than alert in many, many ways ;]