Giving up. Trying to register with Microsoft's "Healthvault"

https://account.healthvault.co.uk/signup/new

Ignoring privacy issues, let's just imagine I want to sign up for the service above. One of the mandatory fields is "Date of birth". However, no matter what I put in that field, I always get the error "date is not valid". No hint of format, not even a datepicker. Anyone here from MS that can hit these guys with a clue-stick ??