Does observe_field work with date_select?

I can’t get observe_field to do anything with my date_select. Here’s the
rhtml code:

<%= date_select ‘course’, ‘lab_start_date’ %>

<%= observe_field(:course_lab_start_date, :frequency => 0.5,
:update => :course_lab_start_date_div, :url => {
:action => ‘preview_text’}) %>

My ‘preview_text’ action is never called. Looking at the html generated,
date_select generates three seperate select fields, and none of them
have id’s. observe_field of course watches for the id…

Any ideas? Any ideas that don’t involve having three seperate selects,
each with their own observe_field? I really want to treat this as a
single date object.