wp_gdsr_render_article and $stars_size ?

Hi,

I am trying to set a size for the rating images. So I add the variable $stars_size=12 into the wp_gdsr_render_article function.

Like this:
wp_gdsr_render_article($stars_size=12);

But the image size is not changing. Anybody know why?

http://wordpress.org/extend/plugins/gd-star-rating/