General Support: Advice on PHP associative array variable for Plogger function

Hello,

We use a unique header file include for Plogger, but would like to use our standard header include for the entire Web site. Our site works by extracting values from an array based on page name to create page-unique string variables. In an attempt to make one header do the job for every page, we added the following code

<!--BEGIN Head Include 1-->
<?PHP
if(empty($strHeadInc1))
{echo '';}
else
{echo $strHeadInc1;}
?>
<!--END Head Include 1-->

For the Plogger page the array variable HeadInc1 contains the following value:
<?PHP the_gallery_head(); ?>

For pages other than the Plogger gallery, this code does not cause problems, but it is not working on the Plogger gallery page. A view source shows the value <?PHP the_gallery_head(); ?> as text, so it is not actually being evaluated as a PHP command.

What am I doing wrong?

Thanks,

Brian

P.S. I am a volunteer and our entire Web site implementation including Plogger has been a combination of intuition and generous help from forum participants across the Internet!