Birth date's format in Address Book?

This could be silly but I can't figure out the correct format for a contact's birth date in Address Book. I'm trying to set 'em up so they'd show up in iCal.

But for some reason it always resets the date to the current date, regardless of my input. I've tried every imaginable combination of formats (dd.mm.yyyy - yyyy.mm.dd. - mm.dd.yyyy - dd/mm/yyyy - yyyy/mm/dd - mm/dd/yyyy - etc.) but none of them seems acceptable. Once I hit enter it resets the date to the current date. Well... on some occasions it accepts the new day but the month remains the same (August in this case).

(And yep, I added the Birthday-field for all contacts from the preferences. )

Not a big deal really, but it annoys the living crap out of me..

Is the AB just so shabby or is there something wrong with the program/OS X/me?

cheers,