Top menu buttons disapeared

On my latest projekt www.kasaero.de i've tried to establish multilingual content. So I've set up everything twice (German and English), all menues, all menue entries, all modules and all articles. Upon saving them, all was set into the respctive content language.
After doing so with the modules, the top menue was gone. I have no idea where my mistake is. Thanxx for helping me out...

Cheers Robin

Do you have language selector module on page?
Do you have two menu modules for both German and English language?
What happens when you manually append /de or /en to append bar URL?

Send link

The selector module is left.
Yes I have 2 menue modules for both languages, in English the top menu works
Manual switching worke as well, but in German no Top Menu buttons..

kasaero.de/

I see the menu when I go to German language, just that module needs setting Menu Tag ID = nav

You're awesome...that was it. Thank you so much!!!

Beside that, any idea what the error on the English start page could be?

Check if your DB is u to date , "Extension Manager", "Database" tab