Where are date_select_tag?

Hi!
I want a date_select_tag inside a form_tag

But it does not work!

I looked for the docs at:

And even, if I copy the code right inside - there are an error!

ActionView::Template::Error (can’t convert Symbol into String) on line
#30 of /Users/kb1/code/rails/rateurdate/app/views/miniprofile/
meantimes/show_birthdate.fbml.erb:
27:

t(‘miniprofile.meantimes.show_birthdate.headline’<br /

<%=
t(‘miniprofile.meantimes.show_postcode.subtitle’) %>


28: <% form_tag meantime_miniprofile_url(:type
=> :birthdate), :method => :post do |f| %>
29:



30: <%= date_select(“post”, “written_on”) %>
31:



32:

33:

app/views/miniprofile/meantimes/show_birthdate.fbml.erb:30:in

block in _render_template__2824634172748094325_2184188140_3813724702546118430' app/views/miniprofile/meantimes/show_birthdate.fbml.erb:28:in _render_template__2824634172748094325_2184188140_3813724702546118430’
app/controllers/miniprofile/meantimes_controller.rb:10:in `show’

This is the whole code:
<% form_tag meantime_miniprofile_url(:type => :birthdate), :method
=> :post do |f| %>




<%= date_select(“post”, “written_on”) %>









<%= image_submit_tag “btn-weiter.png” %>

<% end -%>