Custom library extending custom libraries

[eluser]Spockz[/eluser]
I'm trying to get my custom libraries to extend eachother. However if I extend a custom classfile I get a 'class not found' error in the file 'my_library.php'. I can resolve this by including a 'include' command. However this is not a nice solution, as I'd rather use the autoloader.

I've got the following code:

Code:

class My_Controller extends Controller{
  function __construct() {
    $this->load->library('my_library');
  }
}

Now i've the file 'my_library.php'. Placed in the application/libraries directory.

Code:

class My_Library extends My_Parentlibrary {
  ...
}

The file 'my_parentlibrary.php' contains the class:

Code:

class My_Parentlibrary {
  ...
}

Is there anyone familiar with this problem? Or knows a solution to this?