doubt with helper

Hi all

I need help

I have in my application helper this function:

def example
  content_for(:meta) do
    'okis dokis'
  end
end

And in my main layout view:

..
- yield(:meta)
...

And in other view layer this:

...
- example
...

In development mode all this works, but in production in a server
doesn't work.
what is the problem, I can't explain

Ok

this is application helper:

module ApplicationHelper
  def seo_meta
    content_for(:meta) do
      "<meta content='keywords' name='keywords' />"
    end
  end
end

My template (application.html.erb):

<%= yield(:meta) %>
...

My other view that yields (index.html.erb):

<%= seo_meta %>