Visual Studio Debugger Issue

Hi,
 
If my C# program throws an error, I debug it. But sometimes if I debug, one of this two things are happening:

• My program is running fine when I debug it.
• My program doesn't throw an error, but it doesn't return what I want.

I'm using VS 2012 Express For Windows Desktop.
 
For example, I've this code:

void Form1_Load(object sender, EventArgs e)
{
  HttpWebRequest hwr =   (HttpWebRequest)HttpWebRequest.Create("[URL TO ANY WEBSITE]");
            hwr.Proxy = new WebProxy("1.1.1.1");
            hwr.ProtocolVersion = HttpVersion.Version11;
            HttpWebResponse resp = (HttpWebResponse)hwr.GetResponse();
            System.IO.StreamReader sr = new System.IO.StreamReader(resp.GetResponseStream());
            string s = sr.ReadToEnd();
            sr.Close();
            richTextBox1.Text = s;
}

This throws an exception "Unable to connect to the remote server", because I don't have a proxy with 1.1.1.1 as IP. But if I debug, I don't get an error, just an empty rich text box.
 
What's the reason for this?
Thanks in advance.