posting twitter updates using oauth and java question

I'm trying to post to the twitter update status api using oauth and I'm getting a 401 without any other error information.  I'm posting to http://api.twitter.com/1/statuses/update.xml with a parameter of status="testing twitter!" and a access token and access secret generated by twitter/oauth.  I've tried generating new tokens both for the twitter application and the twitter user account.  I feel everything is valid, any ideas?

"<?xml version => "1.0" encoding="UTF-8"?>
<hash>
  <request>/1/statuses/update.xml</request>
  <error>Could not authenticate you.</error>
</hash>"

http request is:
"HTTP request => POST /1/statuses/update.xml
Content-Type: application/x-www-form-urlencoded
User-Agent: Jakarta Commons-HttpClient/3.1
Host: api.twitter.com
Content-Length: 277

status=testing%20Twitter%21&oauth_token=sWtx2nmAyBaFLzh5WbR6gGRHV9KjF7TFnioJCt87ubs&oauth_consumer_key=Xc8W0rJuwkLPdfTngewBg&oauth_signature_method=HMAC-SHA1&oauth_timestamp=1271968710&oauth_nonce=162012765462908&oauth_version=1.0&oauth_signature=KrLsQjVHUKoZHVPgAaKCqSXLdDI%3D"

response is:
"HTTP response => HTTP/1.1 401 Unauthorized
Date: Thu, 22 Apr 2010 20:38:33 GMT
Server: hi
Status: 401 Unauthorized
WWW-Authenticate: Basic realm="Twitter API"
X-Runtime: 0.00163
Content-Type: application/xml; charset=utf-8
Content-Length: 143
Cache-Control: no-cache, max-age=1800
Set-Cookie: guest_id=127196871321167215; path=/; expires=Sat, 22 May 2010 20:38:33 GMT
Set-Cookie: _twitter_sess=BAh7CDoPY3JlYXRlZF9hdGwrCPxJPicoAToHaWQiJTg1ZjE0YzNmYjMyZjFm%250AZjM3MTdmNDM3MTAxNGEyODI5IgpmbGFzaElDOidBY3Rpb25Db250cm9sbGVy%250AOjpGbGFzaDo6Rmxhc2hIYXNoewAGOgpAdXNlZHsA--4b722ac7a438e73c757947649e1d189f1fc9f29a; domain=.twitter.com; path=/
Expires: Thu, 22 Apr 2010 21:08:33 GMT
Vary: Accept-Encoding
Connection: close

<?xml version="1.0" encoding="UTF-8"?>
<hash>
  <request>/1/statuses/update.xml</request>
  <error>Could not authenticate you.</error>
</hash>
"