I need to post on Facebook fan page, and i am unable to post until i debug the code line by line

I need to post on Facebook fan page, and i am unable to post until i debug
the code line by line

I am posting on facebook through my web application, The problem I am
facing is that, when debug the code line by line message got posted on
page but when execute it on click function it does not. I am unable to
understand this behaviour. Can anyone please help me out?
protected void btnAddPostToPage_Click(object sender, EventArgs e) { var
pageID = Session["SelectedPageID"] != null ?
Session["SelectedPageID"].ToString() : string.Empty; if
(string.IsNullOrEmpty(pageID)) {
Response.Redirect("FBpageToCreateSC.aspx"); }
string app_id = "";
string app_secret = "";
string scope = "publish_stream,manage_pages";
if (Request["code"] == null)
{
Response.Redirect(string.Format(
"https://graph.facebook.com/oauth/authorize?client_id={0}&redirect_uri={1}&scope={2}",
app_id, Request.Url.AbsoluteUri, scope));
}
else
{
Dictionary<string, string> tokens = new Dictionary<string,
string>();
string url =
string.Format("https://graph.facebook.com/oauth/access_token?client_id={0}&redirect_uri={1}&scope={2}&code={3}&client_secret={4}",
app_id, Request.Url.AbsoluteUri, scope,
Request["code"].ToString(), app_secret);
HttpWebRequest request = WebRequest.Create(url) as
HttpWebRequest;
using (HttpWebResponse response = request.GetResponse() as
HttpWebResponse)
{
StreamReader reader = new
StreamReader(response.GetResponseStream());
string vals = reader.ReadToEnd();
foreach (string token in vals.Split('&'))
{
//meh.aspx?token1=steve&token2=jake&...
tokens.Add(token.Substring(0, token.IndexOf("=")),
token.Substring(token.IndexOf("=") + 1,
token.Length - token.IndexOf("=") - 1));
}
}
string access_token = tokens["access_token"];
var client = new FacebookClient(access_token);
client.Post(string.Concat("/PageId/feed"),new { message =
"Message Text " + Guid.NewGuid().ToString().Substring(0,4) });
}
}
}