为什么Javascript调用Page WebMethod导致"500:未知的Web方法"？

我在CreateTicket.aspx.cs中有一个包含此方法的页面:

[WebMethod()]
public static string Categories()
{
    var business = new CategoryBusiness();
    var categories = business.ListRootCategories();

    return categories.Json();
}

和页面上的javascript/jquery代码(同一页面,.aspx):

function LoadRootCategories() {
    PageMethod("CreateTicket.aspx", "Categories", [], LoadCategoriesSucceded, LoadCategoriesFailed);
}


function PageMethod(page, fn, paramArray, successFn, errorFn)  
{
    //Create list of parameters in the form:  
    //{"paramName1":"paramValue1","paramName2":"paramValue2"}  
    var paramList = '';  
    if (paramArray.length > 0)  
    {  
        for (var i=0; i 0) paramList += ',';  
                paramList += '"' + paramArray[i] + '":"' + paramArray[i+1] + '"';  
        }  
    }  
    paramList = '{' + paramList + '}';  
    //Call the page method  
    $.ajax({  
        type: "POST",  
        url: page + "/" + fn,  
        contentType: "application/json; charset=utf-8",  
        data: paramList,  
        dataType: "json",  
        success: successFn,  
        error: errorFn
    });
}

在firebug上运行它,我在控制台上收到以下错误:

500 Internal Server Error
Unknown web method Categories.
[ArgumentException: Unknown web method Categories.
Parameter name: methodName]
   System.Web.Script.Services.WebServiceData.GetMethodData(String methodName) +517489
   System.Web.Handlers.ScriptModule.OnPostAcquireRequestState(Object sender, EventArgs eventArgs) +168
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +68
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

为什么会这样？

我解决了这个问题.

发生了什么事？有点蠢(像往常一样):

CreateTicket.aspx页面声明中缺少"Inherits"属性,因此CreateTicket.aspx.cs未绑定为部分类,即使使用CodeBehind属性也是如此.