Thank you for your patience. Chaning regional settings also helped not. The file seems to be ok. I run it on an other computer and it has all functioned. What not funtioned was then to just copy the installed files on my computer. I could start the config-programm and chose 1024, but it the game it was still 800x600 and on the in-programm settings screen there appeared no 1024.
But anyway - I have now installed so many other mods and especialy the
Historical Das Boot Periscope Screen with Switchable Views 
which seems to exists only in 800x600. So even when the 1024 resolution would work, I would stay with 800 anyway.
But many thanks again.
