(VB.net, Ajax, Json)User ajax Json to set session variables.

I am developing two pages. 

On the first page, if user click a button("Download word file"), client side gets the html code in the specific <div>-tag then using ajax json to assign this value to session variable. script code is like this:

<script type="text/javascript">
        var myDivObj = document.getElementById("testhtmltoword");
        var data = "{Name:'myPageHTML'" + ", Value:'" + myDivObj.innerHTML + "'}";
        $.ajax({
            type: "POST",
            url: "WebService1.asmx/SetSessionValue",
            data: data,
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (msg) {
                alert("success");
            },
            error: function (err) {
                alert(data);
            }
        });</script>

In the web service WebService1.asmx) I created a function(SetSessionValue(Name, Value)), code like below:

<WebMethod(EnableSession:=True)> _
    Public Sub SetSessionValue(ByVal Name As String, ByVal Value As String)
        Dim sessionVal As String = String.Empty
        'If Not Session Is Nothing Then
        Session(Name) = Value
        'End If
    End Sub

However, the session variable Session("myPageHTML") can't be set.

P.S :  I solve it myself.

The solution is very simple, I did not put declaration on the top of the code.

' To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.<System.Web.Script.Services.ScriptService()>

After I put this in the webservice file, the ajax could visit this function and I got what I wanted.

Thank you all.