How do I wait for certain user response in Discord.net? : After asking a question in a channel

    await channel.SendMessageAsync("question?");

how do I wait for a certain response? (eg. yes, no)
I've tried

    string input;
    bool done = false;
    while(!done)
    {
         input = channel.GetMessageAsync(channel.Id).ToString();
         if (String.Compare(input, "yes") == 0)
         {
              //code here
              done = true;
         }
         else if (String.Compare(input, "no") == 0)
         {
              //code here
              done = true;
         }
    }

but it doesn't seem to work.