observe_field on select in IE

I'm using observe_field on a 'select' and it works beautifully in FF
and Safari. It doesn't work at all in IE7.

Here's a snippet:

<%= f.select :project_id, addresses_array %>

<%= observe_field 'listing_project_id', :update => :address, :with
=> :listing_project_id,
    :on => "onselect", :url => { :action => :find_address } %>

<div id="address">

Any ideas why it doesn't work in IE7? I've google'd a lot and there
don't seem to be much talk about this which leads me to believe I
might being doing it wrong. I'm using Rails 2.1.0.

Thanks for the help!


Apparently IE doesn't like what I'm returning in my js.erb file.

If I only put the string 'foo' or '<p>foo</p>' in there, it works. I
had some <dt>..<dd> tags which it doesn't like and won't render.