Variables/Include Problem

I am having some problems using variables in included files. Can someone please look at my code below and see how I might accomplish what I am trying to do? <?php $subnav = "home"; include("incHeader.php"); ?> <!--- CONTENT AREA ---> The content would go here. <!--- END CONTENT AREA ---> <?php include ("incFooter.php"); ?> Now, when I try to reference the subnav variable in the inHeader.php or incFooter.php files, it comes up blank. I am basically trying to adjust the navigation on each page depending on the page I am on. I am just learning PHP, have programmed in ColdFusion for years and in ColdFusion this was not a problem. Any ideas? Eric Fleming