How to get Instagram photo posts when entering profile username using Instagram API

I would like to make a script which gets an Instagram user’s posts by just entering the username - something like this one works, please see the screenshot: http://prntscr.com/sm2kb0

Using this code I plan to get the User ID:

$access_token = 'YOUR ACCESS TOKEN';
$username = 'username';
$user_search = rudr_instagram_api_curl_connect("https://api.instagram.com/v1/users/search?q=" . $username . "&access_token=" . $access_token);
// $user_search is an array of objects of all found users
// we need only the object of the most relevant user - $user_search->data[0]
// $user_search->data[0]->id - User ID
// $user_search->data[0]->first_name - User First name
// $user_search->data[0]->last_name - User Last name
// $user_search->data[0]->profile_picture - User Profile Picture URL
// $user_search->data[0]->username - Username

$user_id = $user_search->data[0]->id; // or use string 'self' to get your own media
$return = rudr_instagram_api_curl_connect("https://api.instagram.com/v1/users/" . $user_id . "/media/recent?access_token=" . $access_token);

//var_dump( $return ); // if you want to display everything the function returns

foreach ($return->data as $post) {
    echo '<a href="' . $post->images->standard_resolution->url . '"><img src="' . $post->images->thumbnail->url . '" /></a>';
}

Then I`m trying to use this code:

$access_token = 'YOUR ACCESS TOKEN';
$username = 'rudrastyh';
$user_search = rudr_instagram_api_curl_connect("https://api.instagram.com/v1/users/search?q=" . $username . "&access_token=" . $access_token);
// $user_search is an array of objects of all found users
// we need only the object of the most relevant user - $user_search->data[0]
// $user_search->data[0]->id - User ID
// $user_search->data[0]->first_name - User First name
// $user_search->data[0]->last_name - User Last name
// $user_search->data[0]->profile_picture - User Profile Picture URL
// $user_search->data[0]->username - Username

$user_id = $user_search->data[0]->id; // or use string 'self' to get your own media
$return = rudr_instagram_api_curl_connect("https://api.instagram.com/v1/users/" . $user_id . "/media/recent?access_token=" . $access_token);

//var_dump( $return ); // if you want to display everything the function returns

foreach ($return->data as $post) {
    echo '<a href="' . $post->images->standard_resolution->url . '"><img src="' . $post->images->thumbnail->url . '" /></a>';

Could somebody tell me what I`m doing wrong? Many thanks