Valum's file uploader - Laravel

Question

Im using Valum's file uploader in Laravel framework. I have this code in my view:

                <div id="file-uploader">        
                    <noscript>          
                        <p>Please enable JavaScript to use file uploader.</p>
                    </noscript>         
                </div>

                <script>     

                    function createUploader(){            
                        var uploader = new qq.FileUploader({

                            element: document.getElementById('file-uploader'),
                            action: 'file-uploader/server/php.php',
                            debug: true,

                        });           
                    }

                    window.onload = createUploader;     
                </script> 

When i want to upload file im not getting any error, but result is "Upload failed" and in console is:

  [uploader] xhr - server response received
  fileuploader.js:1016 [uploader] responseText = 

Documentation states:

It should be {success:true} for completed requests. If it's not, then you have a problem with your server-side script.

Server-side script is original. Now what should I do?