Storing Dropbox Authentication?

I am trying to create a WordPress plugin that exports each blog post to my dropbox folder. The code is below but I have a problem.

If I run this code outside WordPress, it works perfectly. The table is created and my token is stored. If I use a different browser it works perfectly…no authentication because it reads from the DB.

My problem is that when I put this into my plugin, the table is not created at all. So if I go to a different browser, I have to re-authenticate.

Help please.

Code:

/*
 * Copyright 2012 Erin Dalzell.
 *
 */

require_once('Dropbox/API.php');
require_once('Dropbox/Exception.php');
require_once('Dropbox/OAuth/Consumer/ConsumerAbstract.php');
require_once('Dropbox/OAuth/Consumer/Curl.php');
require_once('Dropbox/OAuth/Storage/Encrypter.php');
require_once('Dropbox/OAuth/Storage/StorageInterface.php');
require_once('Dropbox/OAuth/Storage/Session.php');
require_once('Dropbox/OAuth/Storage/Filesystem.php');
require_once('Dropbox/OAuth/Storage/PDO.php');

include ABSPATH . '/wp-config.php';

function etd_initialize() {

global $current_user;

    // Set your consumer key, secret and callback URL
    // should be in the settings
    $key      = 'xxxxx';
    $secret   = 'yyyyy';
    $current_user = wp_get_current_user();

    // Check whether to use HTTPS and set the callback URL
    $protocol = (!empty($_SERVER['HTTPS'])) ? 'https' : 'http';
    $callback = $protocol . '://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];


    // Instantiate the Encrypter and storage objects
    $encrypter = new DropboxOAuthStorageEncrypter('XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX');

    // Instantiate the database data store and connect
    $storage = new DropboxOAuthStoragePDO($encrypter, 1);
    $storage->connect(DB_HOST, DB_NAME, DB_USER, DB_PASSWORD);

    $storage = new DropboxOAuthStorageSession($encrypter);

    $OAuth = new DropboxOAuthConsumerCurl($key, $secret, $storage, $callback);

    $dropbox = new DropboxAPI($OAuth);

    return $dropbox;

}

function export_to_dropbox($id) {
    $dropbox = etd_initialize();

    $post = get_post($id);


    // Create a temporary file and write some data to it
    $tmp = tempnam('/tmp','dropbox');
    file_put_contents($tmp, $post->post_content);

    // Upload the file with an alternative filename
    $put = $dropbox->putFile($tmp, $post->post_title . '.md');

    // Unlink the temporary file
    unlink($tmp);
}

register_activation_hook( __FILE__, 'etd_initialize' );
add_action('publish_post', 'export_to_dropbox');
?>