Dynamic Log In / Out button required

[shippers]

Zen Cart v1.3.9e
The site has never been upgraded
The site is not live yet - nearly there :)

I have trawled the fora, and have not found the answer, so here goes.

I have my online shop set up in a subfolder named "products" of my domain - e.g. www.mydomain.com/products. I have my own banner and top menu that is used consistently across the entire site, and the zen cart menu and content resides below the main banner and menu system. All is good.

What I have done is incorporate the "Log In / Out" link into my main top menu. This I have only been partly successful with.

The issue is the "Log in / Out" will only appear in my top menu when users are browsing in the "products" area. If the user navigates to the "about us" or the "home" page (or anywhere outside of products), the function that determines whether to display "log in" or "log out" does not work, and a blank space is displayed instead.

The code I have inserted into my top menu reads thus:

[FONT="Courier New"]===

<div class="menu_bar_right_button">
<?php if ($_SESSION['customer_id']) { ?>
<li><a href="<?php echo zen_href_link(FILENAME_LOGOFF, '', 'SSL'); ?>"><?php echo HEADER_TITLE_LOGOFF; ?></a></li>
<?php
} else {
if (STORE_STATUS == '0') {
?>
<li><a href="<?php echo zen_href_link(FILENAME_LOGIN, '', 'SSL'); ?>"><?php echo HEADER_TITLE_LOGIN; ?></a></li>
<?php } } ?>
</div>

===[/FONT]

I don't believe the issue is to do with the zen_href_link, FILENAME_LOGIN or FILENAME_LOGOFF bits, as I have replaced these entire sections with HTML without success. The issue appears to be with $_SESSION customer_id. Quite how to resolve this, I am not sure.

Any assistance regarding this matter would be greatly received.

[Kim]

Your URL?

[shippers]

www.mailmetric.com

To get into the products area:

username temp
password chicken

Payment gateway not set up yet, so products area is currently protected.

[Kim]

Why not just use Zen Cart for the "front" page and then you don't have to fiddle with sessions etc in another application?

[shippers]

I did consider this once this issue was encountered. However, it would require quite a bit of re-work. Additionally, I plan to incorporate forum functionality plus other bits and pieces in the future. Shoving all of this into the root folder would get somewhat messy.

It would be nice to be able to keep the zen cart functionality in it's own "products" folder, and be able to utilise the session whilst navigating outside of products. I know this is possible as the session is effectively still alive, but would like some guidance if possible.