visual_effect check_box

Am I even close on how to do this? I've googled alot and still can;t
get this to work

<tr><td>
  <p>
    <b>Monday</b>
    <%= f.check_box :monday %>
    <%= observe_field(:monday_checked, :function =>
visual_effect('appear', 'monday-div')) %>
    <%= observe_field(:monday_unchecked, :function =>
visual_effect('fade', 'monday-div')) %>
  </p>
<div id='monday-div'><div>
  <p>
    <b>Start</b><br />
    <%= f.time_select :monday_start, :twelve_hour => true %>
  </p>

  <p>
    <b>End</b><br />
    <%= f.time_select :monday_end, :twelve_hour => true %>
  </p>
</div></div>