PDO Class Fatal Error: Call to a member function prepare() on a non-object [Solved] [duplicate]

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  Call to a member function on a non-object [duplicate]
  
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I seem to be having some issues loading my site using a PDO class I found here:
http://culttt.com/2012/10/01/roll-your-own-pdo-php-class/

I have built the code on a local MAMP server using php 5.5.18 and everything seems to work fine, however when I upload it to my web server I get the following error:

PHP Fatal error:  Call to a member function prepare() on a non-object in /global/classes.php on line 51

I have compared phpinfo() on both my localhost and server and I can't see any major discrepancies in configurations different directory paths and the odd extension version being .1-.3 versions older than the localhost are the main differences however both servers are using php 5.5.18.

The class that I am using is:

//Define Database Vars based on Site Mode
if($config_sitemode=='dev'){
    define("DB_HOST", $config_devdbhost);
    define("DB_USER", $config_devdbuser);
    define("DB_PASS", $config_devdbpass);
    define("DB_NAME", $config_devdbname);
    define("DB_PREFIX", $config_devdbprefix);
}
elseif($config_sitemode=='live'){
    define("DB_HOST", $config_livedbhost);
    define("DB_USER", $config_livedbuser);
    define("DB_PASS", $config_livedbpass);
    define("DB_NAME", $config_livedbname);
    define("DB_PREFIX", $config_livedbprefix);
}
else{
    echo 'Error Connecting to Database: Invalid Site Mode';
}

// Database Class
class Database{
    private $host   = DB_HOST;
    private $user   = DB_USER;
    private $pass   = DB_PASS;
    private $dbname = DB_NAME;

    private $dbh;
    private $error;
    private $stmt;

    public function __construct(){
        // Set DSN
        $dsn = 'mysql:host=' . $this->host . ';dbname=' . $this->dbname;
        // Set options
        $options = array(
            PDO::ATTR_PERSISTENT    => true,
            PDO::ATTR_ERRMODE         => PDO::ERRMODE_EXCEPTION
        );
        // Create a new PDO instanace
        try{
            $this->dbh = new PDO($dsn, $this->user, $this->pass, $options);
        }
        // Catch any errors
        catch(PDOException $e){
            $this->error = $e->getMessage();
        }
    }

    public function query($query){
        $this->stmt = $this->dbh->prepare($query);
    }

    public function bind($param, $value, $type = null){
        if (is_null($type)) {
            switch (true) {
                case is_int($value):
                $type = PDO::PARAM_INT;
                break;
                case is_bool($value):
                $type = PDO::PARAM_BOOL;
                break;
                case is_null($value):
                $type = PDO::PARAM_NULL;
                break;
                default:
                $type = PDO::PARAM_STR;
            }
        }
        $this->stmt->bindValue($param, $value, $type);
    }

    public function execute(){
        return $this->stmt->execute();
    }

    public function resultset(){
        $this->execute();
        return $this->stmt->fetchAll(PDO::FETCH_ASSOC);
    }

    public function single(){
        $this->execute();
        return $this->stmt->fetch(PDO::FETCH_ASSOC);
    }

    public function rowCount(){
        return $this->stmt->rowCount();
    }

    public function lastInsertId(){
        return $this->dbh->lastInsertId();
    }

    public function beginTransaction(){
        return $this->dbh->beginTransaction();
    }

    public function endTransaction(){
        return $this->dbh->commit();
    }

    public function cancelTransaction(){
        return $this->dbh->rollBack();
    }

    public function debugDumpParams(){
        return $this->stmt->debugDumpParams();
    }
}

Line 50, 51, 52 are:

public function query($query){
    $this->stmt = $this->dbh->prepare($query);
}

When I am calling the database I am using this code:

$database = new Database();
$database->query('SELECT firstname, surname, username, role FROM '.DB_PREFIX.'staffprofiles WHERE sid = :sid');
$database->bind(':sid', $sid);
$result = $database->single();

If anyone is able to help me and shed some light on to why I might be receiving these errors I would appreciate your help

Edit: Problem solved, had to look closer at where I defined the database variables and it pointed me to a typo.