strange php output

I'm trying to do a little trick with my new site. i have one main php script, index.php which includes the header and footer scripts and the page script between them. the page script is determined by $page, which is set to "main" if it doesnt exist already. $page . ".php" is then included. I have one other page so far, "datetime.php". I wanted to let datatime run itself by including the headers and footers on its own if it wasnt included by index.php. so, i add this to the top and similar code at the bottom (replaced header with footer): <? if (!$page=="datetime") // Not using index.php { include("header.php"); } ?> this code works when datetime.php is included by index.php, but on its own the script just outputs <html><body></body></html>. Even ignoring the xhtml code outside the php code in the file. its like the entire file is ignored. i really have no clue why. anyone else have one?