German layout with japanese keyboard.

Hello,

I needed a Macbook pro with japanese keyboard, but here in germany I can't order it. So a normal german MBP was ordered and a japanese keyboard as »repair«. The store installed it along with a new blank harddisk and I was happy for the first time.
At home I installed the software from the two dvd which came with the MBP and choosed as language of the system german and as keyboard ことえり (kotoeri).
The problem is, that every time a input field get focus, the german keyboard layout is active when romaji shall be used (the input menu show still the kotoeri symbol, but the inputs are from the german layout - inclusive umlauts). Only after explicit pressing the 英数 key (left at the space key) the correct romaji layout is used. The onscreen keyboard layout says first german and after the romaji key it switched to U.S. layout (correct for the aspect).
It looks like the MBP still thinks, that the german keyboard is installed and only after pressing a specific japanese key it will be switched to the correct layout for some time. I reset already the PMU and the parameter memory (that with command-alt-p-r at the start of the system).
What else can I do to complete the keyboard switch?

Thanks in advance,
Gregor Féng