Rails 4.1 undefined method `usual_start_time' for nil:NilClass

I have a form which creates the default time of 6.45pm. When a new form is created

_form.html.erb

 = f.input :started_at, as: :string, class: 'form-control', input_html: { value: l(@happening.started_at, format: :date_time_picker), class: 'date_time_picker' }, label: "Start at"

but instead of showing 1845 in my happenings controller i want to replace it with the usual_start_time field in my areas table

scheme.rb

create_table "areas", force: :cascade do |t|
    t.string  "deprecated__default_postcode", limit: 255
    t.integer "number_of_runners_needed",                 default: 100,     null: false
    t.string  "referral_partners_logo_image"
    t.integer "address_id"
    **t.string  "usual_start_time",                         default: "18:45"**
  end

I have tried using

time = DateTime.strptime((Date.today + 1.day).to_s + ' ' + **"#{@area.usual_start_time}"**, '%Y-%m-%d %H:%M')

but it gives me undefined method `usual_start_time' for nil:NilClass

also tried

time = DateTime.strptime((Date.today + 1.day).to_s + ' ' + **"#{@area.happenings.usual_start_time}"**, '%Y-%m-%d %H:%M')

happenings_controller.rb (want to replace "18.45"

  def new
    @type = params[:type].underscore
    time = DateTime.strptime((Date.today + 1.day).to_s + ' ' + **"18:45"**, '%Y-%m-%d %H:%M')
    @happening = Happening.new(started_at: time)
  end