yahoo contacts fetch using asp net and c#

I am facing the problem in content fetching form yahoo. Previously this code is working fine for me. Now I am getting this error.The remote server returned an error: (401)Unauthorized.

I am using this code in below link.

http://www.codeproject.com/Articles/91646/Implementing-Yahoo-Contact-Reader-Using-ASP-NET

please help me out. or provide me anyother code.