Hmm. Thanks for this hint.
I don't have a 'mods'-directory in openxcom. All my mods are in 'standard' - Maybe i did something wrong, when installing openxcom, a few years ago...
That's funny, my program has several hundred downloads, but nobody reports an error. Because my program searches in the wrong folder (or other users also have their mods in 'standard') and doesn't find the rulesets in the mods and the enhanced mode shouldn't work properly.