Twitter API call returns error 34 in Wordpress

<?php

///
//  Raw, standalone PHP file
///

function rawTwitterCache_cacheTweets() {
    require_once("twitteroauth/twitteroauth.php");

    $userName = (isset($_REQUEST['username'])) ? $_REQUEST['username'] : '';
    $tweetCount = (isset($_REQUEST['count'])) ? $_REQUEST['count'] : '';

    $consumerKey = 'CONMSUMER_KEY';
    $consumerSecret = 'SHH_CONSUMER_SECRET';
    $accessToken = '_ACCESS_TOKEN';
    $accessTokenSecret = 'QUIET!_TOKEN_SECRET';

    $connection = new TwitterOAuth($consumerKey, $consumerSecret, $accessToken, $accessTokenSecret);

    if ($userName) {
        $tweets = $connection->get("https://api.twitter.com/1.1/statuses/user_timeline.json?screen_name=" . $userName . "&count=" . $tweetCount);
    }

    echo json_encode($tweets);
}

rawTwitterCache_cacheTweets();  //  Returns JSON object of tweets

///
//  Virtually Wordpress function
///

function vnmTwitterCache_cacheTweets() {
    require_once("twitteroauth/twitteroauth.php");

    $userName = get_option('vnmTwitterCache_twitterName');
    $tweetCount = get_option('vnmTwitterCache_tweetCount');

    $consumerKey = get_option('vnmTwitterCache_consumerKey');
    $consumerSecret = get_option('vnmTwitterCache_consumerSecret');
    $accessToken = get_option('vnmTwitterCache_accessToken');
    $accessTokenSecret = get_option('vnmTwitterCache_accessTokenSecret');

    $connection = new TwitterOAuth($consumerKey, $consumerSecret, $accessToken, $accessTokenSecret);

    if ($userName) {
        $tweets = $connection->get("https://api.twitter.com/1.1/statuses/user_timeline.json?screen_name=" . $userName . "&count=" . $tweetCount);
    }

    $jsonArray = array();
    $jsonArray['response'] = $tweets;
    echo json_encode($jsonArray);
    die();
}

add_action('wp_ajax_cacheTweets', 'vnmTwitterCache_cacheTweets');   //  Call to 'cacheTweets' via Ajax, scheduled event or similar returns JSON object with message: 'Sorry, that page does not exist'

?>