Use Playstation Plus voucher in another country?

I recently bought 2 Playstation Plus vouchers in Switzerland. One was for a friend who lives in Germany. She has tried to enter and it is always with her that it is invalid or wrong and if I enter it with me, both go code (of course I have not confirmed that I really want to redeem the code!)

Above the voucher is Sony eVoucher (Switzerland) But then there's something below Europe with the voucher.

No, she can't redeem him in Germany

Is not it synonymous if I log in with their account and redeem it? Or is she then banished?

I do not know that