c# - yammer get user token yammer REST API -

i'm trying add user yammer group, need have token of user whom want add group. i've used following endpoint access user token

https://api.yammer.com/api/v1/oauth/tokens.json?user_id={0}&consumer_key={1} 

for consumer_key i'm passing clientid of yammer application i've created (using verified admin account).

the problem user endpoint working fine , returning me json response. user endpoint returning "the remote server returned error: (400) bad request."

please, find code below

private yammerjsonusercontract getuserdetailsfromyammer(string userid, string clientid)     {         yammerjsonusercontract objuser = null;         try         {             string url = string.format(this.userimpersonationurl, userid, clientid);             string jsonstring = postyammerjson(url, this._adminaccesstoken, "get");             yammerjsonusercontract [] objusercollection = newtonsoft.json.jsonconvert.deserializeobject<yammerjsonusercontract[]>(jsonstring);             objuser = objusercollection[0];         }         catch (exception ex)         {             throw ex;         }         return objuser;     } private string postyammerjson(string url, string accesstoken, string httpmethod)     {         string json = string.empty;         try         {              httpwebrequest yammerrequest = httpwebrequest.create(url) httpwebrequest;             yammerrequest.method = httpmethod;             yammerrequest.contenttype = "application/json; odata=verbose";             yammerrequest.accept = "application/json; odata=verbose";             yammerrequest.contentlength = 0;             yammerrequest.headers.add("authorization", string.concat("bearer ", accesstoken));             using (httpwebresponse response = yammerrequest.getresponse() httpwebresponse)             {                 encoding encode = encoding.getencoding("utf-8");                 streamreader reader = new streamreader(response.getresponsestream(), encode);                 json = reader.readtoend();             }         }         catch (exception ex)         {             throw ex;         }         return json;     } 

can please let me know i'm missing , why api returning user details users not all.

waiting response.

cheers amlan

this long shot maybe need add authorization header request value "oauth".

something like:

request.headers.authorization = oauth;