Categories are not displayed in Oscommerce 2.3

I updated my OsCommerce shop to 2.3.3.4:

I replaced all files with the new default files from the package.
I Updated the old database with the script here: https://stackoverflow.com/a/19806818/1069083
Compared an sql-dump of the old database with the dump of an empty new database, It looked all OK.

Now the new version works with all products in it, but although I activated the "Categories" box in the admin interface it is not shown on the left.

Did I forget a Detail?

Solution

I found out why:

there are two different configure.php files, one is in

catalog/includes/configure.php

and one is in

catalog/admin/includes/configure.php

I didn't set the database to the new database in the admin config file, so all changes in admin didn't affect the real shop