What is the folder structure of your WEB site? In particular, where is the page that you have inserted the code above?

Probably the printLatestImagesByMtime() function was not coded to be able to be called anywhere but from the zenphoto index.php folder.

The site structure is
public_html/test/photos

the page is in 'test'
public_html/test/zen.php

I am not sure why the link would not work, then. But anyway, if you want to experiment make the following changes:

Thanks for the help! Here's what I have

Warning: require_once(0/template-functions.php) [function.require-once]: failed to open stream: No such file or directory in /home/xxx/public_html/test/zen.php on line 3

Fatal error: require_once() [function.require]: Failed opening required '0/template-functions.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/xxx/public_html/test/zen.php on line 3

Both photos and zp-core should have been within quotes. Sorry about that.

Just to add that function does not rely on any context so it should work that way.

It's working now. Thanks sbillard!