General Support: inlude plogger in smarty tpl?

Hello,
I want to include plogger in a site that consists out of .tpl files (smarty).

The first line of header.tpl is:
{php} include("./plogger/gallery.php"); {/php}
In the head section of the header.tpl is:
{php} the_gallery_head(); {/php}

The kiekjes.tpl is the page that should include the plogger gallery.
The first line is:
{include file='header.tpl'}
and somewhere below it reads:
{php} the_gallery(); {/php}

However the result contains errors:
http://www.plaatstaal.net/index.php?page=kiekjes

I am pretty certain that plogger is correctly installed, check out the link below (regular .php file):
http://www.plaatstaal.net/gallery.php

Please help me!
Thank you

-Johan