Authorizing a request


I am trying to send a tweet from my microcontroller using C.
I make a connection to via a TCP port and send the following information over the socket: (my key and token have been masked for security).

POST /1/statuses/update.json?include_entities=true HTTP/1.1
Accept: */*
Connection: close
User-Agent: OAuth gem v0.4.4
Content-Type: application/x-www-form-urlencoded
Authorization: OAuth oauth_consumer_key="xxxxxxxxxxxxxxxxxxxxx", oauth_nonce="kZmiSDRZ8t0XLNmTdPdtdeP0TgeRfNEwQHq2iqew", oauth_signature="vKfAlI1ylvaV0LaYNnYS4LAlymk%3D", oauth_signature_method="HMAC-SHA1", oauth_timestamp="1343244092", oauth_token="nnnnnnnnn-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", oauth_version="1.0"
Content-Length: 14


(Under Accept: the code box omits the asterisks but they are there)
The status is not posted, so I was wondering if you see any other reasons why the post would not work.
I can assure you that the oauth signature is generated correctly. The timestamp is received via an NTP request to
Since this is on a microcontroller, I will not see a response from twitter.