ASPX How to get the form initiated from OperatePage - actually should be the existing instance

I have a simple VB.Net web app that gets a large table based on Form controls and I need it display the progress such as Doing 'Record# nnn'.
 
This method can be simulated with via clicking on a button the the form is initiated which is the instance that we need to access. lblMsg is a label on the form what I would like to update.

PublicFunction GetTable
   Dim I asIntegerfor I = 1to10
      lblMsg.Text = "Doing Record# "& i
      Sleep 1000nextEndFunction

 
We are currently trying the below but when GetTable gets control lblMsg is nothing which means that the form is not initialed.
 
How can I get this to work?

$(document).ready(function () {
 
                    $("#btnTrial").click(function (e) {
 
                        e.preventDefault();
                        $("#btnTrial").attr('disabled', 'disabled');
 
                        var total = 5;
                        if (document.getElementById('<%=txtLoopRows.ClientID %>').value != "") {
                            var total = document.getElementById('<%=txtLoopRows.ClientID %>').value;
                        }
                        // comes here the first time
                        PageMethods.OperatePage(total, function (result) {
 

                            if (result) {
                                setTimeout($.updateProgressbar, 500);
                            }
                        });
                    });
                });

 

<System.Web.Services.WebMethod(EnableSession:=True)> _
    PublicSharedFunction OperatePage(total AsInteger) AsObject 
        Dim session As HttpSessionState = HttpContext.Current.Session
 
        Dim totalParsed AsInteger = 0Integer.TryParse(total.ToString(), totalParsed)
        _TotalLoop = totalParsed  ' 1

        System.Threading.ThreadPool.QueueUserWorkItem(AddressOf ThreadProc, session)  '  Sets to invoke ThreadProc
ReturnNewWith {.progress = 0}
    EndFunction

 

<System.Web.Services.WebMethod(EnableSession:=True)> _
    PublicSharedFunction ThreadProc(ByVal stateInfo AsObject) '2
'  Loops with sleep but sets StateVariable to the counter which is picked up by Progress Page then to $.updateProgressbar = function
'  InfusionSoft stuff here
Dim DefPage AsNew _Default
        DefPage.GetTable(stateInfo)  ' Invokes but form variables are nothing 

        stateInfo("TICK") = NothingEndFunction

Thanks