0x80070005 (E_ACCESSDENIED)当搜索htmlelement时

我试图找到一个页面上的提交按钮，并使用web浏览器提交表单，这部分代码一直给我

An unhandled exception of type 'System.UnauthorizedAccessException' occurred in System.Windows.Forms.dll
Additional information: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))

代码是:

     HtmlDocument pagehtml = this.webBrowser1.Document;
     HtmlElementCollection page = pagehtml.All;
                foreach (HtmlElement element in page)
                {
                    if (element.GetAttribute("type") == "submit") //line that is highlighted during the error
                    {
                        element.InvokeMember("click");
                    }
                }

                HtmlElementCollection page = webBrowser1.Document.GetElementsByTagName("input");
                foreach (HtmlElement element in page)
                {
                    if (element.GetAttribute("value").Contains("Submit"))
                    {
                        element.InvokeMember("click");
                    }
                }