Hello, does anybody know who is the producer of Nokia tags which come with the 6212 classic ?

We have tested a lot (30 different brand/models) of mifare standard tags (smartcard size, stickers, etc):
some of them have troubles with 6212 (not with 6131), some can be read only turning the display of the 6212 while touching them.

From our experience, only the three original Nokia-labeled tags which come with the phone can be read even without touching the phone, one inch away...so we're wondering where we can buy them!