RadComboBoxContext problem

[Sri]

Hi,

I am using a redcombobox with loadondemand with a web service.

I am trying to add a property appContext to Radcombobox context as shown below.

When I click on the combo, the call goes to webservice, but I am unable to get the added property appContext in the webservice method. This is happening only when I open a popup and close it and adding the value from the popup to the combo.
Here I can see only the added item but not all the items of the combo.

Adding appContext:
public IEnumerable<ScriptDescriptor> GetScriptDescriptors()
        {
            var descriptor = new ScriptControlDescriptor("Sales.Purchase.Controls.SalesSelector", Panel.ClientID);

            var appContext = new ApplicationContext();

            appContext.DecryptedRequestContext[AppContext.SystemIdRequestKey] = salesId;
            appContext.DecryptedRequestContext["id"] = SelectedSaleTypeId;
            appContext.DecryptedRequestContext["sv"] = sales.Text;
            appContext.DecryptedRequestContext["prid"] = SaleReqID.ToString();


            descriptor.AddProperty("btnDummy", Page.ClientScript.GetPostBackEventReference(btnDummy, String.Empty, true));
            descriptor.AddProperty("appContext", appContext.EncryptedRequestContext);
            descriptor.AddComponentProperty("SalesList", cboSales.ClientID);
           
            return new ScriptDescriptor[] { descriptor };
        }

WebService Method:
I am unable to find the key "appContext"
public RadComboBoxData GetSalesData(RadComboBoxContext context)
        {
            const int itemsPerRequest = 20;

            var comboData = new RadComboBoxData();
                       
            var encryptedContext = context.ContainsKey("appContext") ? (string)context["appContext"] : null;
            .......
            return comboData;
        }

Please help me out