HTML element invokemember("click") is not working

Hi all,

  I am trying to search using Google search engine with bulk data from excel sheet.Everything is working fine but after processing some data from excel, execution stops processing a particular data.The problem is htmlelement invokemember is not working and throws no exception.

My code is,

 foreach (HtmlElement dfghjg in webBrowser1.Document.GetElementsByTagName("button"))
                            {
                                if (dfghjg.Name == "btnG")
                                    dfghjg.InvokeMember("click");
                                s = false;
                                t = true;
                            }