Showing error messages in active admin for has many relationship

I am facing an issue showing up the error messages in active admin.

I get all the error messages displayed with the fields in the form. But in the code below, I need atleast one skill and maximum 5 skills to be added. Else need to throw an error message.

I’ve added a validation in model as :

validates :skills, :length => { :minimum => 1, :maximum => 5, :message => " should be atleast 1 and less than 5"}

This validates perfectly, but no error message is displayed.

Can anyone help me with the display of the error message.

Following is the code :

form :html => { :enctype => “multipart/form-data” } do |f|

f.inputs "User", :multipart => true do

    f.input :    name
f.input :email,  :as => :    email
f.input :    profile_name
f.input :    date_of_birth
f.input :gender,  :as => :select, :collection => Gender::  GENDERS
  f.inputs "Skills* ( minimum 1 & maximum 5 )" do
    f.has_many :skills do |p|
      if !p.object.nil?
        # show the destroy checkbox only if it is an existing appointment
        # else, there's already dynamic JS to add / remove new appointments
        p.input :_destroy, :as => :boolean, :label => "Destroy?",
                :hint => "Check this checkbox, if you want to delete this field."
      p.input :      description
p.input :    title