Urgent !!! WebClient Help Needed

Hi 2 all,
I am trying to download pdf files from website.Website requires Login & UserName.I am using this code but doesn't work.Any help will be appreciated !! Code i am usign

string url="MyWebsite/page1.pdf";
string FileName=@"C:\abc.pdf";
WebClient Wc=new WebClient();
NetWorkCredential nc=new NetworkCredential("MyUserName","MyPassword");
Wc.Credentials=nc;
Wc.DownloadFile(url,FileName);