Problemer med at inserte data og uploade billed.

PHP kode 

 <form action="register.php" name="login" method="post">
             <br />
             <?php
             if ($_POST) {
                 $username = htmlentities($_POST['username']);
                 $password = $_POST['password'];
                 $SPS       = $_POST['SPS'];
                 $email       = htmlentities($_POST['email']);
                 $name       = htmlentities($_POST['name']);
                 $last       = htmlentities($_POST['last']);
                 
                 /*IMG SETTINGS*/
                 $img_name = $_FILES['img']['name'];
                 $img_type = $_FILES['img']['type'];
                 $img_size = $_FILES['img']['size'];
                 $img_tmp  = $_FILES['img']['tmp_name'];
                 $ext = substr($img_name, strrpos($img_name, '.'));
                 
                 if ($username && $password && $SPS && $email && $name && $last) {
                     if( $stmt = $mysqli->prepare("SELECT * FROM `users` WHERE username='$username' AND email='$email'")) {
                     $stmt->bind_param('t', $_GET['username']);
                     $stmt->execute();
                     $result = $stmt->get_result();
                     $row = $result->fetch_assoc();    
                         if ($row = 0) {
                         $password = md5($password  . $username . $salt);
                         $password = sha1($password);
                         $SPS = md5('s334sytgehnfyt3hrfen4' . $salt . 'feshnDE45r' . $password . $SPS);
                         $SPS = sha1($SPS);
                         
                         /*Uploading image*/
                         
                         if ($img_name) {
                             move_uploaded_file($img_tmp, "avatar/$username.$ext");
                             $avatar = "avatar/$username.$ext";    
                         }
                         echo $avatar;
                         $date = date("Y/M/D h:i:s");
                         $sql = "INSERT INTO `users`(`id`, `username`, `password`, `SPS`, `name`, `last_name`, `joined`, `bio`, `channel_name`, `channel_desc`, `group`, `profile_img`, `avatar`) VALUES (?,'$username','$password','$SPS','$name','$last','$date','','','','1','$avatar','')";
                         
                             if ($newuser = $mysqli->query($sql)) {
                                 echo 'You have a new user created, and you will also get a email from us.';
                             } else {
                                 echo 'Can\'t insert data to the database.';    
                             }
                         } else {
                             echo 'The username or email is already in use!.';    
                         }
                     }
                 } else {
                     echo 'All field with * is requried.';    
                 }
             }
             ?>
             <label for="username">Username *</label><br />
             <input type="text" name="username" id="username" placeholder="Write your username" /><label for="img" class="fakebtn">Profile image</label><br />
             <label for="password">Password *</label><br />
             <input type="password" name="password" id="password" placeholder="Write your password" /><br />
             <label for="SPS">Special password (can be anything) *</label><br />
             <input type="password" name="SPS" id="SPS" placeholder="Write your Speical password" /><br />
             <label for="email">Email *</label><br />
             <input type="email" name="email" id="email" placeholder="Write your email" /><br />
             <label for="name">Name *</label><br />
             <input type="text" name="name" id="name" placeholder="Write your name" /><br />
             <label for="last">Last name *</label><br />
             <input type="text" name="last" id="last" placeholder="Write your last name" /><br />
             <input type="file" name="img" id="img" style="display:none;" /><br /><br />
 
             <input type="submit" value="Register" />
         </form>