https access not working after upgrade to 1.3.6

I've recently upgraded from 1.3.5 to 1.3.6.
I tested the upgrade before overwriting the directory with the original files. Everything worked (including https) access to secure pages.

I've since overwritten the new directory with the old directory (not inc the config.php files - they are still intact) Everything works except accessing secure pages (https) such as the "login" page.

When I click "login" it takes the user to a secure page (https) and I get this error message:

Fatal error: Call to undefined function: zen_js_zone_list() in /var/users/vfcoup70/lavenderlane.co.nz/htdocs/lavenderstore/includes/modules/pages/login/jscript_addr_pulldowns.php on line 32

Have you come across this error before?

Kind regards,

This is located in the file:
/includes/functions/functions_general.php

It sounds like you have not upgraded all of your files properly on your site or that you have an add-on that has overwritten the file with an old version ...

Get a clean Zen Cart v1.3.6 and unzip to an empty directory on your computer ...

Using something like Beyond Compare from scootersoftware.com you can check to see what files are different to the files you have on your site and the originals ...