Why does this series of media queries not work?

Head out to http://newhopeforyou.com/mobile/about.php. I've got my stylesheet set up like this:

header("Content-type: text/css; charset: UTF-8");
<?php require_once('stylesheet_1024.php'); ?>
<?php require_once('stylesheet_800.php'); ?>
<?php require_once('stylesheet_768.php'); ?>
<?php require_once('stylesheet_480.php'); ?>
<?php require_once('stylesheet_320.php'); ?>

It works great on my box, in that I can proof ever set of media queries and see that everything lines up accordingly.

When I check it on my mobile device, however, when I go from landscape to portrait, there's no change. I'm on an iPhone with dimensions of 320 X 480. When I go back and forth between the two views, my CSS doesn't display the 480 and I can't figure out why.

I'm stoked about this particular approach in the way I can organize and manipulate my settings, but I'm missing something and I don't know what.

BTW: Every file is set up as @media screen and (min-width: 320px) {, @media screen and (min-width:480) { etc.

What am I missing?
Bruce GustPHP DeveloperAsked:
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Look into how to format the actual Media Query state fir IPhone.  I remember reading that there is an alternate way to do it.  You may need to add the MAX and Min width to each statement.

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