date_selec Feb and date problem

Hi,

I am using the following for date of birth.

<%= date_select 'attending_ip', 'dob', :order =>
[:month, :day, :year], :use_month_numbers => true, :include_blank =>
true, :start_year => 1950, :end_year => Time.now.year %>

However, this makes user to enter such a date 02/31/2000 which doesn't
exist. Date drop down menu always displays from 1 - 31. so, if I enter
2/31 and check again, it displays 3/3.

How do I solve this problem?