sidebar not displaying php list

Hi,
I’m using WP2.2.2 and I’d like to place in the sidebar php generated lists such as from the popularity contest. The text is in the form of

<?php akpc_most_popular(); ?>

The problem is that it doesn’t display anything in the sidebar, but if I put the same code into a post, then the list is being displayed (I’m using the Exec-PHP plugin). It also doesn’t work in the sidebar with the default template and other plugins which generate php list don’t work either.

Any clues why this would be?

Thanks