[Plugin: NextGEN Gallery] post thumbnail with wrong titel

I use the feature post thumbnail. It works with images from WP media pool.
If i use pictures from the gallery NextGen, the image is perfectly true, but unfortunately the text displayed incorrectly!
Text as the name of the gallery is used.
To fix the error, I tried to work with the following code:

PHP Code:

<php
  $ attr = array (
 'title' => 'test',
 );
 the_post_thumbnail ($ size = 'post-thumbnail', $ attr);
 ?>

Now I have to say that the attributes do not work for the images from NextGen. The pictures from the media pool so that I can change the attributes.

Does anyone have any idea?

http://wordpress.org/extend/plugins/nextgen-gallery/