HttpRequest with SSL

Have this code:

The problem is that internet browser show popup "Do you want to use this certificate...", but in my application this message doesn't show up, why?

In addition i can say that on other PC all works fine - same project.

All needed capabilities are set. I repeat that this same project works fine on 3 other computers and builds are working fine on test tablets.

private async void Button_Click(object sender, RoutedEventArgs e)
    {
        String url = "https://URL"; //hidden in security purpose
        HttpClientHandler aHandler = new HttpClientHandler();
        aHandler.ClientCertificateOptions = ClientCertificateOption.Automatic;
        HttpClient aClient = new HttpClient(aHandler);
        aClient.DefaultRequestHeaders.ExpectContinue = false;
        aClient.DefaultRequestHeaders.MaxForwards = 3;
        Uri requestUri = new Uri(url);
        HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, requestUri);
        var result = await aClient.GetAsync(requestUri, HttpCompletionOption.ResponseContentRead);
        var responseHeader = result.Headers;
        var responseBody = await result.Content.ReadAsStringAsync();

    }

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Foma