Problems with saving variables in MYSQL

Question

I am currently building up a website where the user can sign in with his steam account. For that purpose I am using a Steam Authentication Library which you can find here: https://github.com/SmItH197/SteamAuthentication

What I want to do is to save the ID64, the name and the link to the users avatar in my MYSQL database when the user logs into my site. Those things are included in the variables $steamid64, $steamname & $steamavatar. I have written following script to achieve this:

<?php
require '../steamauth/steamauth.php';

if(isset($_SESSION['steamid'])) {

    include_once 'connect.php';
    include_once '../steamauth/userInfo.php';

    $steamid64 = mysqli_real_escape_string($conn, $_SESSION['steam_steamid']);
    $steamname = mysqli_real_escape_string($conn, $_SESSION['steam_personaname']);
    $steamavatar = mysqli_real_escape_string($conn, $_SESSION['steam_avatar']);

    //Error handlers
    //Check for empty fields
    if(empty($steamid64) || empty($steamname) || empty($steamavatar)) {
        header("Location: ../?userdata=empty");
        exit();
    } else {
        //Check if input characters are valid
        if (!preg_match("/^[0-9]*$/", $steamid64)) {
            header("Location: ../?userdata=invalid");
            exit();
        } else {
            //Insert USERDATA into database
            $sql = "INSERT INTO `users` (`steamid64`, `name`, `avatar`) VALUES ('$steamid64', '$steamname', '$steamavatar')";
            mysqli_query($conn, $sql);
            header("Location: ../?userdata=saved");
            exit();
        }
    }

} else {
    header("Location: ../");
    exit();
}

?>

The script checks if the user is signed in by "if(isset($_SESSION['steamid]))", then proceeds to go through some error handlers and then sends a query to my database inserting the information that are in my variables.

My problem is that my script doesn't work, I am not sure what exactly is happening (that's why I am asking) but it just doesn't create a new entry in my database.

Below you can find steamauth.php, connect.php and userInfo.php. I hope this is enough to solve my problem. If you need any more information do not hesitate to comment below, I will gladly provide it. Thank you for your effort!

steamauth.php: https://github.com/SmItH197/SteamAuthentication/blob/master/steamauth/steamauth.php

userInfo.php:

<?php
if (empty($_SESSION['steam_uptodate']) or empty($_SESSION['steam_personaname'])) {
    require 'SteamConfig.php';
    $url = file_get_contents("http://api.steampowered.com/ISteamUser/GetPlayerSummaries/v0002/?key=".$steamauth['apikey']."&steamids=".$_SESSION['steamid']); 
    $content = json_decode($url, true);
    $_SESSION['steam_steamid'] = $content['response']['players'][0]['steamid'];
    $_SESSION['steam_communityvisibilitystate'] = $content['response']['players'][0]['communityvisibilitystate'];
    $_SESSION['steam_profilestate'] = $content['response']['players'][0]['profilestate'];
    $_SESSION['steam_personaname'] = $content['response']['players'][0]['personaname'];
    $_SESSION['steam_lastlogoff'] = $content['response']['players'][0]['lastlogoff'];
    $_SESSION['steam_profileurl'] = $content['response']['players'][0]['profileurl'];
    $_SESSION['steam_avatar'] = $content['response']['players'][0]['avatar'];
    $_SESSION['steam_avatarmedium'] = $content['response']['players'][0]['avatarmedium'];
    $_SESSION['steam_avatarfull'] = $content['response']['players'][0]['avatarfull'];
    $_SESSION['steam_personastate'] = $content['response']['players'][0]['personastate'];
    if (isset($content['response']['players'][0]['realname'])) { 
           $_SESSION['steam_realname'] = $content['response']['players'][0]['realname'];
       } else {
           $_SESSION['steam_realname'] = "Real name not given";
    }
    $_SESSION['steam_primaryclanid'] = $content['response']['players'][0]['primaryclanid'];
    $_SESSION['steam_timecreated'] = $content['response']['players'][0]['timecreated'];
    $_SESSION['steam_uptodate'] = time();
}
$steamprofile['steamid'] = $_SESSION['steam_steamid'];
$steamprofile['communityvisibilitystate'] = $_SESSION['steam_communityvisibilitystate'];
$steamprofile['profilestate'] = $_SESSION['steam_profilestate'];
$steamprofile['personaname'] = $_SESSION['steam_personaname'];
$steamprofile['lastlogoff'] = $_SESSION['steam_lastlogoff'];
$steamprofile['profileurl'] = $_SESSION['steam_profileurl'];
$steamprofile['avatar'] = $_SESSION['steam_avatar'];
$steamprofile['avatarmedium'] = $_SESSION['steam_avatarmedium'];
$steamprofile['avatarfull'] = $_SESSION['steam_avatarfull'];
$steamprofile['personastate'] = $_SESSION['steam_personastate'];
$steamprofile['realname'] = $_SESSION['steam_realname'];
$steamprofile['primaryclanid'] = $_SESSION['steam_primaryclanid'];
$steamprofile['timecreated'] = $_SESSION['steam_timecreated'];
$steamprofile['uptodate'] = $_SESSION['steam_uptodate'];
// Version 3.2
?>

connect.php (connection settings for mysql):

<?php
$dbServername = "removed";
$dbUsername = "removed";
$dbPassword = "removed";
$dbName = "removed";

$conn = mysqli_connect($dbServername, $dbUsername, $dbPassword, $dbName);