1 error prohibiting this request from being saved: Tought must exist

I am new using ruby on rails, and what I want to do is to use the information from another form generated with scaffold, in the requested tab, I want to call the field of tpedido and the information appears in the form, but at the moment to save it, I get the error of the title.

My requested model:

class Pedido < ApplicationRecord

has_many :solicitud
belongs_to :tpedido


end

controlador 

class PedidosController < ApplicationController


 before_action :set_pedido, only: [:show, :edit, :update, :destroy]

  # GET /pedidos
  # GET /pedidos.json
  def index
    @pedidos = Pedido.all
  end

  # GET /pedidos/1
  # GET /pedidos/1.json
  def show
  end

  # GET /pedidos/new
  def new
    @pedido = Pedido.new

  end

  # GET /pedidos/1/edit
  def edit
  end

  # POST /pedidos
  # POST /pedidos.json
  def create
    @pedido = Pedido.new(pedido_params)



    respond_to do |format|
      if @pedido.save
        format.html { redirect_to @pedido, notice: 'Pedido was successfully created.' }
        format.json { render :show, status: :created, location: @pedido }
      else
        format.html { render :new }
        format.json { render json: @pedido.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /pedidos/1
  # PATCH/PUT /pedidos/1.json
  def update
    respond_to do |format|

      if @pedido.update(pedido_params)
        format.html { redirect_to @pedido, notice: 'Pedido was successfully updated.' }
        format.json { render :show, status: :ok, location: @pedido }
      else
        format.html { render :edit }
        format.json { render json: @pedido.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /pedidos/1
  # DELETE /pedidos/1.json
  def destroy
    @pedido.destroy
    respond_to do |format|
      format.html { redirect_to pedidos_url, notice: 'Pedido was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_pedido
      @pedido = Pedido.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def pedido_params
      params.require(:pedido).permit(:Nombre, :Direccion, :telefono, :campana, :placa, :zona, :ncaja, :tipopedido)
    end
end

modelo tpedido

    class Tpedido < ApplicationRecord

    has_many :pedido
    accepts_nested_attributes_for :pedido

end

controlador Tpedido

    class TpedidosController < ApplicationController
  before_action :set_tpedido, only: [:show, :edit, :update, :destroy]

  # GET /tpedidos
  # GET /tpedidos.json
  def index
    @tpedidos = Tpedido.all
  end

  # GET /tpedidos/1
  # GET /tpedidos/1.json
  def show
  end

  # GET /tpedidos/new
  def new
    @tpedido = Tpedido.new
  end

  # GET /tpedidos/1/edit
  def edit
  end

  # POST /tpedidos
  # POST /tpedidos.json
  def create
    @tpedido = Tpedido.new(tpedido_params)

    respond_to do |format|
      if @tpedido.save
        format.html { redirect_to @tpedido, notice: 'Tpedido was successfully created.' }
        format.json { render :show, status: :created, location: @tpedido }
      else
        format.html { render :new }
        format.json { render json: @tpedido.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /tpedidos/1
  # PATCH/PUT /tpedidos/1.json
  def update
    respond_to do |format|
      if @tpedido.update(tpedido_params)
        format.html { redirect_to @tpedido, notice: 'Tpedido was successfully updated.' }
        format.json { render :show, status: :ok, location: @tpedido }
      else
        format.html { render :edit }
        format.json { render json: @tpedido.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /tpedidos/1
  # DELETE /tpedidos/1.json
  def destroy
    @tpedido.destroy
    respond_to do |format|
      format.html { redirect_to tpedidos_url, notice: 'Tpedido was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_tpedido
      @tpedido = Tpedido.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def tpedido_params
      params.require(:tpedido).permit(:tipopedido)
    end
end

form donde me muestra el select

    <div class="field">
    <%= form.label :tipo_de_pedido %>
    <%= form.collection_select :tpedido_tipopedido, Tpedido.all, :id, :tipopedido %>

  </div>

schema.db

    # This file is auto-generated from the current state of the database. Instead
# of editing this file, please use the migrations feature of Active Record to
# incrementally modify your database, and then regenerate this schema definition.
#
# Note that this schema.rb definition is the authoritative source for your
# database schema. If you need to create the application database on another
# system, you should be using db:schema:load, not running all the migrations
# from scratch. The latter is a flawed and unsustainable approach (the more migrations
# you'll amass, the slower it'll run and the greater likelihood for issues).
#
# It's strongly recommended that you check this file into your version control system.

ActiveRecord::Schema.define(version: 20181228010838) do

  create_table "pedidos", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=latin1" do |t|
    t.string "Nombre"
    t.string "Direccion"
    t.string "telefono"
    t.string "campana"
    t.string "placa"
    t.string "zona"
    t.string "ncaja"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.bigint "tpedido_id"
    t.index ["tpedido_id"], name: "index_pedidos_on_tpedido_id"
  end

  create_table "solicituds", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=latin1" do |t|
    t.date "fecha"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.bigint "user_id"
    t.bigint "pedido_id"
    t.index ["pedido_id"], name: "index_solicituds_on_pedido_id"
    t.index ["user_id"], name: "index_solicituds_on_user_id"
  end

  create_table "tpedidos", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=latin1" do |t|
    t.string "tipopedido"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
  end

  create_table "users", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=latin1" do |t|
    t.string "nombre", default: "", null: false
    t.string "apellido", default: "", null: false
    t.string "email", default: "", null: false
    t.string "encrypted_password", default: "", null: false
    t.string "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.boolean "superadmin_role", default: false
    t.boolean "admin_role", default: false
    t.boolean "user_role", default: true
    t.index ["email"], name: "index_users_on_email", unique: true
    t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
  end

  create_table "vehiculos", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=latin1" do |t|
    t.string "marca"
    t.string "vehiculo"
    t.string "placa"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.bigint "user_id"
    t.index ["user_id"], name: "index_vehiculos_on_user_id"
  end

  add_foreign_key "pedidos", "tpedidos"
  add_foreign_key "solicituds", "pedidos"
  add_foreign_key "solicituds", "users"
  add_foreign_key "vehiculos", "users"
end

thanks in advance.