c# - Etsy API says UnAuthorized(401) when fetching access_token -

i following this question connect etsy api , have written following code:

class etsy     {         private const string access_token = "jagbkdwqii82lhiaj2pqcujd ";         private const string secret = "is1bztdh2k";         private const string base_url = "https://openapi.etsy.com/v2";         private string token = "";         public etsy()         {             string f = "";             try             {                  var request_token_url = base_url + "/oauth/request_token";                 var oauth = new manager();                 oauth["consumer_key"] = access_token;                 oauth["consumer_secret"] = secret;                 oauth.acquirerequesttoken(request_token_url, "post");                 f = "required tokens = " + oauth["token"].tostring();                 token = f;             }             catch (exception ex)             {                 console.writeline("exception: "+ex.message);                 token = "exception :\n"+ex.message;             }          }         public string show()         {             return token;         }     } 

when running code keeps giving unauthorized(401) error. same credentials use etsy python library works fine. doing wrong?

update:

i debugged further , found it's sending following headers:

header:- oauth oauth_callback="oob", oauth_consumer_key="jagbkdwqii82lhiaj2pqcujd", oauth_nonce="150z8543", oauth_signature="4qgkvgbif%2bqpoyncnnwwniirhjo%3d", oauth_signature_method="hmac-sha1", oauth_timestamp="1431409362", oauth_version="1.0" 

is missing?