nextgen-gallery error message in plugin check

Have placed the short link in theme:
<?php echo do_shortcode( “[NextGEN]” ); ?>

am getting this message when I run the plugin check:

“Missing the call to wp_head() in your theme, contact the theme author”

What do I need to put into the theme?

thanks!

https://www.ads-software.com/extend/plugins/nextgen-gallery/