YARPP using 150×150 Thumbnails

Hi there,

I got the same problem as Mr Eddy in this thread describes:
http://wordpress.org/support/topic/yarpp-not-using-the-square-thumbnails?replies=17

I want YARPP to use the already existing 150×150 thumbnails and resize them to 120x120px instead of using the original size and resize them.

I did exactly what was descibed in the post above. At least I think I did. ^^

I put this code into the function.php right before “?>”:
add_image_size( 'yarpp-thumbnail', $width = 150, $height = 150, true );

I also used the recommended plugin to regenerate the thumbnails, but nothing has changed.

The result can be seen here (I didn’t resize them yet, because I wanted do make sure YARPP uses the right picture)

As you see YARPP uses this picture.
I want it to use this one (150×150)

I hope I could point my problem out well enough. I am not a nativ speaker.