I have enabled avatar in Settings > Discussion. But the avatar won't show up at all, both in comment and in post. Only the default avatar (Mystery Man) showed up.
I've tried those lines:
<?php echo get_avatar( $id_or_email, $size = '96' ); ?>
<?php echo get_avatar( $comment, 32 ); ?>
<?php echo get_avatar( $id_or_email, $size, $default, $alt ); ?>
But none of those work. Oddly, the avatar shows up properly in Twenty Ten theme, but not in other themes. Any help?