"Currently unavailable" for one variation

Hello

I have a new variation of an existing product listed on Amazon Germany marketplace.

If I go to Amazon.de and try to buy my product (for testing purposes) then if I change the delivery address to some other country besides Germany, then it shows that the product is ‘Currently unavailable’. What could be the reason and from where I could change the settings, so that delivery to other countries will be possible as well?

There is no such problem for the existing variation, it can be shipped to everywhere. I am an user of Amazon FBA.

Best regards
Sander