Oauth returns Could not verify OAuth request.

#!php
<?php
try {
	// fetch access_token
	$oauthHeader = array(
		&#x27;oauth_consumer_key&#x27; => StringUtil::trim(BITBUCKET_PUBLIC_KEY),
		&#x27;oauth_nonce&#x27; => StringUtil::getRandomID(),
		&#x27;oauth_signature_method&#x27; => &#x27;HMAC-SHA1&#x27;,
		&#x27;oauth_timestamp&#x27; => TIME_NOW,
		&#x27;oauth_version&#x27; => &#x27;1.0&#x27;,
		&#x27;oauth_token&#x27; => $_GET[&#x27;oauth_token&#x27;]
	);
	$postData = array(
		&#x27;oauth_verifier&#x27; => $_GET[&#x27;oauth_verifier&#x27;]
	);
	
	$signature = $this->createSignature(&#x27;https://bitbucket.org/!api/1.0/oauth/access_token&#x27;, array_merge($oauthHeader, $postData));
	$oauthHeader[&#x27;oauth_signature&#x27;] = $signature;
	
	$request = new HTTPRequest(&#x27;https://bitbucket.org/!api/1.0/oauth/access_token&#x27;, array(), $postData);
	$request->addHeader(&#x27;Authorization&#x27;, &#x27;OAuth &#x27;.$this->buildOAuthHeader($oauthHeader));
	$request->execute();
	$reply = $request->getReply();
	$content = $reply[&#x27;body&#x27;];
}
catch (SystemException $e) {
	throw new IllegalLinkException();
}

public function buildOAuthHeader(array $parameters) {
	$header = &#x27;&#x27;;
	foreach ($parameters as $key => $val) {
		if ($header !== &#x27;&#x27;) $header .= &#x27;, &#x27;;
		$header .= rawurlencode($key).&#x27;="&#x27;.rawurlencode($val).&#x27;"&#x27;;
	}
	
	return $header;
}

public function createSignature($url, array $parameters, $tokenSecret = &#x27;&#x27;) {
	$tmp = array();
	foreach ($parameters as $key => $val) {
		$tmp[rawurlencode($key)] = rawurlencode($val);
	}
	$parameters = $tmp;
	
	uksort($parameters, &#x27;strcmp&#x27;);
	$parameterString = &#x27;&#x27;;
	foreach ($parameters as $key => $val) {
		if ($parameterString !== &#x27;&#x27;) $parameterString .= &#x27;&&#x27;;
		$parameterString .= $key.&#x27;=&#x27;.$val;
	}
	
	$base = "POST&".rawurlencode($url)."&".rawurlencode($parameterString);
	$key = rawurlencode(StringUtil::trim(BITBUCKET_PRIVATE_KEY)).&#x27;&&#x27;.rawurlencode($tokenSecret);
	
	return base64_encode(hash_hmac(&#x27;sha1&#x27;, $base, $key, true));
}

?>