Critical RadMenu Issue when trying to call via ajax

[Soumadeep]

In a scenario, RadMenu is present in a user control. This user control is bind in the master page of the application. Hence all content pages have this menu. I need refresh only the RadMenu (not the entire page) from the content pages. I did wrap up the RadMenu with an updatepanel. So from my content page via Javasscript (I need to make the refresh via JS)  when I am calling __doPostBack('updatepanel',''). The updatepanel gets call & it reloads it. Since the UserControl(having the RadMenu) is inside the UpdatePanel the same gets called & a postback is incurred in it. This calls the function responsible for populating the menu. However, this time it gives an exception :     

Error: Microsoft
JScript runtime error: Sys.ArgumentTypeException: Object of type
'Telerik.Web.UI.RadMenu' cannot be converted to type 'Sys.UI.Control'.
Parameter
name: instance

Help:
​ - Need to overcome this error    OR   find a different way to handle the above scenario. Any immediate help would be great.