I want to use [a solution by @toscho][1] to display and rotate some quotes. The unchanged code works very well, but if I replace the

    protected function get_rand()
    {
        return rand( 1, 1000 );
    }

with (from [here][2])

    protected function get_rand()
    {
        $array = file("wp-content/plugins/quotes-rotator/quotes.txt");
        $r = rand(0,count($array)-1);
        return $array[rand(0,count($array)-1)];
    }

the code works well only at the first page load, but when I press the 'New' button to display a new quote the system outputs an error:

> Warning: file(wp-content/plugins/quotes-rotator/quotes.txt): failed to
> open stream: No such file or directory in
> /var/www/.../public_html/wp-content/plugins/quotes-rotator/ajax-shortcode-demo.php
> on line 106

**What is wrong here?**

  [1]: http://wordpress.stackexchange.com/a/73009/25187
  [2]: http://wordpress.stackexchange.com/q/72974/25187