HttpContext.Current.Server.Execute(page writer False) Child control not loaded

I have read your post for dynamically load ASP.Net UserControl using jQuery AJAX and Web Service WebMethods. but when iam trying to implement that i am getting a error (executing child request for handler 'system.web.ui.page' in vb.net.).I am getting error on this line "HttpContext.Current.Server.Execute(page, writer, False)" . i think my child control is not loaded

can you please help me as i am new to programming.