issues with recaptcha

CommentsController.rb

class CommentsController < ApplicationController
  def create
    @post = Post.find(params[:comment][:post_id])
    @comment = Comment.new
    @comment.name =  params[:comment][:name]
    @comment.comment = params[:comment][:comment]
    if verify_recaptcha(:model => @comment) && @comment.valid?
      @post.comments << @comment
      redirect_to :back, flash: {message: "Thank you for your comment "}
    else
      @comment.errors.each do |attribute, error|
        flash[attribute] = error
      end
      redirect_to :back
    end

  end
end

  end
end

recaptcha.rb

Recaptcha.configure do |config|
  config.public_key  = '6LeI7wETAAAAALTGxu5UeNAaZhTHem7Ar9g49dXG'
  config.private_key = '6LeI7wETAAAAANW3wF3k3AOcxat6uxhGJHghWKf6'
end