Unauthorze Call error


Hi All

I am getting the un-authorize call when making api call to twitter from my console application, but it is working when I do the same request with fiddler.The header signiture is same in both the cases.
The remote server returned an error: (401) Unauthorized.
and Json error msg is
{“errors”:[{“message”:“Could not authenticate you”,“code”:32}]}

Request Url is https://api.twitter.com/1.1/users/lookup.json?screen_name=sasikander7

and Post Header is-

Authorization: OAuth oauth_consumer_key=“343452345”, oauth_nonce=“d910e9bb9306afb1c2166418bacf7207”, oauth_signature=“ZWdIeY9y%2Ff%2BCMks674sp%2BNjssqY%3D”, oauth_signature_method=“HMAC-SHA1”, oauth_timestamp=“1349707247”, oauth_token=“633872218-23452345”, oauth_version="1.0"
Host: api.twitter.com

Can any body help me in this regard,