Captura de combo box.

Olá. Estou tentando fazer a captura de valores num combobox. Mas só tenho conseguido null. O que há?

@*
 * This template takes a single argument, a String containing a
 * message to display.
 *@
@(message: String)

@*
 * Call the `main` template with two arguments. The first
 * argument is a `String` with the title of the page, the second
 * argument is an `Html` object containing the body of the page.
 *@
@main("Welcome to Play") {

    <h1>Bem-vindo a SEMOB</h1>
    <h3>Consulte a situação de seu veículo</h3>


     <form name= "marcas" id= "marcas" method = "POST">
        <label for="select">Marca</label>
         <select id ="select">
         <option value = "">Escolha a Marca</option>
         <option value="fiat">Fiat</option>
         <option value="WV">Volkswagen</option>
         <option value="GM">Chevrolet</option>    
         <input type="submit" value="submit">   
        </select>

    </form>

}

package controllers;

import javax.inject.Inject;

import play.data.DynamicForm;
import play.data.FormFactory;
import play.mvc.*;
import views.html.*;

public class DetranController extends Controller{

    @Inject
    private FormFactory forms;

    /**
     * home page
     * @return
     */
    public Result index() {
        return ok(index.render("sifu"));
    }

    public Result consultar () {
        DynamicForm dynamicForm = this.forms.form().bindFromRequest();
        String marca = dynamicForm.get("select");
        return ok("marca recebida: " + marca);
    }
}

GET     /                           controllers.DetranController.index
POST    /                            controllers.DetranController.consultar
# Map static resources from the /public folder to the /assets URL path
GET     /assets/*file               controllers.Assets.versioned(path="/public", file: Asset)