or
//example 1htmlControl.InvokeEvent(ScriptEventType.OnMouseOver);//example 2dropDownFilter.SelectByText(option, true); //where true indicates whether to invoke the OnChange eventThread.Sleep(2000);browser.Manager.ActiveBrowser.WaitForAjax(4000);browser.Manager.ActiveBrowser.WaitUntilReady();browser.Manager.ActiveBrowser.AutoDomRefresh = truebrowser.Manager.ActiveBrowser.Frames.RefreshAllDomTrees();browser.Manager.ActiveBrowser.RefreshDomTree();browser.Manager.ActiveBrowser.WaitForElement(new HtmlFindExpression("id=###"), 4000, false);browser.ActiveBrowser.Find.ById<HtmlControl>("lnkCal").MouseClick();browser.ActiveBrowser.Find.ById<HtmlControl>("lnkCal").Click();ArtOfTest.WebAii.Exceptions.ExecuteCommandException : ExecuteCommand failed!InError set by the client. Client Error:System.Runtime.InteropServices.COMException (0x80029C4A): Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)) at mshtml.HTMLDocumentClass.IHTMLDocument3_get_documentElement() at ArtOfTest.InternetExplorer.IECommandProcessor.SetCurrentDocumentMarkup(BrowserCommand& response) at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessInformationCommands(BrowserCommand request) at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessCommand(WebBrowserClass ieInstance, BrowserCommand request, IHTMLDocument2 document)BrowserCommand (Type:'Information',Info:'DocumentMarkup',Action:'NotSet',Target:'null',Data:'',ClientId:'Client_9b8eedd9-e654-4b7e-aa20-b07eb0f72df9',HasFrames:'False',FramesInfo:'',TargetFrameIndex:'-1',InError:'True',Response:'System.Runtime.InteropServices.COMException (0x80029C4A): Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)) at mshtml.HTMLDocumentClass.IHTMLDocument3_get_documentElement() at ArtOfTest.InternetExplorer.IECommandProcessor.SetCurrentDocumentMarkup(BrowserCommand& response) at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessInformationCommands(BrowserCommand request) at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessCommand(WebBrowserClass ieInstance, BrowserCommand request, IHTMLDocument2 document)')InnerException: none.TearDown : System.NullReferenceException : Object reference not set to an instance of an object.at ArtOfTest.WebAii.Core.Browser.ExecuteCommandInternal(BrowserCommand request)at ArtOfTest.WebAii.Core.Browser.ExecuteCommand(BrowserCommand request, Boolean performDomRefresh, Boolean waitUntilReady)at ArtOfTest.WebAii.Core.Browser.RefreshDomTree()at ArtOfTest.WebAii.Core.Browser.ExecuteCommand(BrowserCommand request, Boolean performDomRefresh, Boolean waitUntilReady)at ArtOfTest.WebAii.Core.Browser.ExecuteCommand(BrowserCommand request)at ArtOfTest.WebAii.Core.Browser.InternalNavigateTo(Uri uri)at ArtOfTest.WebAii.Core.Browser.NavigateTo(Uri uri)at ArtOfTest.WebAii.Core.Browser.NavigateTo(String url)at Utilities.WebAii.Navigate(Area area, String url) in WebAii.cs: line 238at Forms.UserUI.PageNavigator.Navigate(String url) in PageNavigator.cs: line 89at Forms.UserUI.UserArea.Navigate(String url) in UserArea.cs: line 59at Tests.Mixed.Test.TestTest() in Test.cs: line 86--TearDownat NUnit.Framework.TestContext.ResultAdapter.get_State()at Tests.BaseTest.TearDownBase() in BaseTest.cs: line 80