GeckoFX60无法触发文档完成事件

Question

public  void useFirefox()
        {

            button2.PerformClick();
            if ((string.IsNullOrEmpty(textBox1.Text) || (string.IsNullOrEmpty(rankDomain.Text))))
            {
                MessageBox.Show("SOme text, you have 60 seconds time.");
                WaitNSeconds(60);
            }
            button1.Enabled = false;
            btnStop.Enabled = true;
            completedkeywordsHelp.Lines = textBox1.Lines;

            for (iGesko = 0; iGesko < textBox1.Lines.Length; iGesko++)
            {
                if (btnStop.Enabled == false)
                {
                    break;
                }
                if (!(textBox1.Lines[iGesko].Equals("")))
                {
                    firefoxBrowser.Navigate("https://www.google.com/search?q=" + textBox1.Lines[iGesko] + "&num=" + resultsPerPage.Text);
                }
                else
                {
                    webBrowser1.Navigate("about:blank");
                    webBrowser1.DocumentText = "No request performed, this is an empty keyword/space.";


            }

-

 private void firefoxBrowser_DocumentCompleted(object sender, EventArgs e)
        {
            MessageBox.Show("entered");
}

加载页面后，它应该触发文档完成的文档，但不会触发。我不确定为什么会这样。我可以看到网页正在加载，但未触发该事件。