remote function not submitting form

Hi all,

I have this code:

    <%= collection_select('declarations_payers', 'user', @users, 'id',
'fullname', {},
        {:onChange => remote_function(
          :update => "participants",
          :url => { :controller => 'ajax',
          :action => 'declaration_users' }
          )
        }
    ) %>

It's inside a div, inside a form generated with form_tag.

But when I change the item of the selectlist, it doesn't submit the
form data. Does anyone know what's the problem?
Or maybe how I can solve this problem. I tried the serialize()
function, but that can only be used for one field.

Thanks in advance!