Shortcode does not run, can't figure it out

Hi!

I have create my own slideshow plugin.
When I use do_shortcode(); everything works fine.

But if I just run the_content();
The shortcode is not executing.

$sprinter_slideshow = new sprinter_slideshow();
class sprinter_slideshow{

	private $data_created = FALSE;
	function sprinter_slideshow(){
		add_shortcode('sprinter_slideshow', array(&$this, 'sprinter_slideshow_shortcode'));

		add_action('init', array(&$this, 'initialize_sprinter'));
		//add_action('the_posts', array(&$this, 'check_for_shortcode'));
	}

as you can see, I create an instance of the class and directly add the shortcode to the register.

What is wrong?

Thanks in advance