umm... first off, you're using include wrongly. The syntax is
include 'stuff';
Second off, that won't work, because that will make PHP look for the file "oldentry.php?argument=something". Thats not what you want, you want it look for the file named "oldentry.php".
Try this:
<?php
$msgpk=2;
include 'oldentry.php';
?>
Make sure the oldentry.php is not expecting the argument to come from the POST method, but the GET method.
