C# - xNet - how to add proxy support

I made a checker for some website, however, I need to add Proxy support:

using (var request = new HttpRequest())
{
       request.Proxy = new HttpProxyClient(ProxyRandom());
}

public static string ProxyRandom()
{
       Random rnd = new Random();
       return Proxies[rnd.Next(0, Proxies.Count)];
}

for some reason, it doesn't work... the program doesn't post any data when I try to use proxies

what is the right way to add proxy support when I use xNet library?