Plugin Problem: Comments with Avatars won’t show?

Hi,

I’ve activated 2 gravitars (My Avatars and WordPress Gravatars) though not both at the same time — and get this error at the bottom of the page:
<…Fatal error: Call to undefined function: gravatar() in /homepages/2/d142238593/htdocs/baldpunk/wp-content/themes/Slurpie/comments.php on line 54

What do I need to do to fix? The comments won’t show.

Page where I get the problem is here:
http://baldpunk.com/2009/05/13/ghost-breath-of-coney-island/

Thanks,
Baldie
http://baldpunk.com