ajax在asp vb .net中返回未定义的值

Question

这是Md.XaYed Asfee，我是asp vb.net的新手我面临一个问题，我不知道为什么，请帮助我... 2013年视觉工作室

这是我的javascript代码

$("#name").blur(function () {
        //e.preventDefault();
        var aData = $("#name").val();
        //alert(aData);
        $.ajax({
            type: "GET",
            //url: "/files/rettxtvalpros.aspx/EmployeeDetails?country_nm='" + aData + "'",
            url: "/master.aspx/EmployeeDetails",
            //data: '{country_nm: "' + aData + '" }',
            data: '{ country_nm:'+ aData +'}',
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (a) {
                var dat = JSON.parse(a.d);
                //var so = dat[1];
                alert(dat);
                //var dat = JSON.parse(a.d);
                //var dat = data.d;
                //var iso = dat[0];
                //$("#iso").val(iso);
                //$("#pname").val() = dat.pname;
                //$("#iso3").val() = dat.iso3;
                //$("#ncode").val() = dat.ncode;
                if (a.d != '')
                {
                    alert("0");
                    //alert(a[0]);
                }
                //if (conf == '')
                //{
                //    alert("Null");
                //}
            },
            failure: function (data) {
                //var r = jQuery.parseJSON(response.responseText);
                //alert("Message: " + r.Message);
                //alert("StackTrace: " + r.StackTrace);
                //alert("ExceptionType: " + r.ExceptionType);
                alert("1");
            }
        });
    });
});

，这是我的vb代码

Imports System
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.ComponentModel
Imports System.Web.Script.Services
Imports System.Web
Imports System.Data.SqlClient
Imports System.Linq
Imports System.Xml
Imports System.Web.Script.Serialization
Public Class master
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    End Sub

    Public Class country
        Public iso As String
        Public name As String
        Public printable_name As String
        Public iso3 As String
        Public ncode As String
    End Class
    Private _name As String
    Public Property country_nm As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property
    <System.Web.Services.WebMethod()> _
    <System.Web.Script.Services.ScriptMethod()> _
    Public Function EmployeeDetails(country_nm As String) As List(Of String)
        Dim objEmployee As New country    ' CREATE AN OBJECT.
        Dim a As New List(Of String)()
        'MsgBox(country_nm)
        Dim conn As String = ConfigurationManager.ConnectionStrings("sQlConn").ConnectionString

        Dim myConn As New SqlConnection(conn)
        Dim objComm As New SqlCommand("SELECT * FROM country_iso WHERE printable_name LIKE '%' + @LookUP + '%' ", myConn)
        'Dim objComm As New SqlCommand("SELECT * FROM country_iso", myConn)
        myConn.Open()

        objComm.Parameters.AddWithValue("@LookUP", country_nm)
        Dim sdr As SqlDataReader = objComm.ExecuteReader()

        'If sdr.Read Then
        'objEmployee.name = sdr("name").ToString()
        'objEmployee.iso3 = sdr("iso3").ToString()
        'objEmployee.ncode = sdr("numcode").ToString()
        'objEmployee.iso = sdr("iso").ToString()
        'objEmployee.printable_name = sdr("printable_name").ToString()
        'End If

        If sdr.Read Then
            a.Add(sdr("iso").ToString())
            a.Add(sdr("name").ToString())
            a.Add(sdr("printable_name").ToString())
            a.Add(sdr("iso3").ToString())
            a.Add(sdr("numcode").ToString())
        End If

        MsgBox(sdr("name").ToString())
        Dim serializer As JavaScriptSerializer
        myConn.Close() : sdr.Close() : Return a
    End Function

End Class

我应用了很多教程但没有找到任何结果......