Error On Video Upload To Page

[sametkarakayali]

I'm getting this error while trying to upload video on the page:

(OAuthException - #1) An unknown error has occurred.

` var fb = new FacebookClient(pageAccessToken);
string attachementPath = filePath;
using (var file = new FacebookMediaStream
{
ContentType = "video/*",
FileName = Path.GetFileName(attachementPath)
}.SetValue(File.OpenRead(attachementPath)))
{
var isim = file.FileName;
dynamic result = fb.Post("/"+ pageid + "/videos",
new { title = PaylasimIcerik, description = PaylasimIcerik,source= file });

                            }`