string translation not working in view,

I haven't change any locales so by default it is set to :en.
In validation error its perfectly picking right string from en.yml.

But still in view for normal string translation its not working. e.g
<%=t :hello %>
is printing "Hello " only.

While my config/locales/en.yml is like below:
en:
  hello: Hello world

en:
  activerecord:
    attributes:
      user:
        uEmail: "E-mail address"
        uPassword: "Password"
        uPassword_confirmation: "Password confirmation"
    errors:
      models:
        user:
          attributes:
            Uemail:
              blank: "is required"

Any suggestion please ?
ruby 1.8.7
rails 3.2.1

Thanks,
Amit Suthar