why my apple id can ONLY using in China?

I am traveling in Japan and bought an APP STORE CARD inorder to charge my ID, but when I doing this in itunes, system refused my requirement and told me that I cannot use this card since I am a CHINESE USER. when i buying this card, I asked the shop assistant whether I can using it in China, and they said that is OK.

Right now I am wondering what should I do now? Let is useless plastic card returned or just seating here and letting my money gone since I am a "CHINESE USER"?

NEED HELP PLEASE!