date_select javascript_tag

Hi

this is ok

<label for="entry_nr_documento">Documento</label> <%= text_field 'entry', 'nr_documento' %> <!-- porta il focus sulla casella di testo --> <%= javascript_tag render(:update) { |page| page['entry_nr_documento'].focus } %>

this no

<label for="entry_data">Data</label> <%= date_select 'entry', 'data', :order => [:day, :month, :year], :start_year => 2006 %> <%= javascript_tag render(:update) { |page| page['entry_data'].focus } %>

err $("entry_data") has no properties

where is the mistake?. thank