System.NullReferenceException: For all Button_Clicks ?

Hello & Thanks ;

I wrote a freeware 'Kid Safe Browser' with VS 2019 vb.net .vb but IE11 has too many limitations .

So I am trying to write it in C# VS .Net Using your code to get me going .

https://foxlearn.com/article/chromium-browser-using-cefsharp-in-csharp-151.html

I am new to C# and CefSharp .

I get the same error msg for each button_click : 

        private void BackBtn_Click(object sender, EventArgs e)
        {
    if (chrome.CanGoBack)
        chrome.Back();
        }

        private void ForwardBtn_Click(object sender, EventArgs e)
        {
    if (chrome.CanGoForward)
    chrome.Forward();
        }

        private void RefreshBtn_Click(object sender, EventArgs e)
        {
    chrome.Refresh();
        }

        private void GotoBtn_Click(object sender, EventArgs e)
        {
            chrome.Load(AddressTxt.Text);
        }

Thanks for your Help...