User input isn't being saved into database?

{{ Form::open(array('action' =>('ProductController@postUseSearch'))) }}
    {{ Form::text('keyword', null, array('placeholder' => 'search by keyword')) }}
    {{ Form::submit('search') }}
    {{ Form::close() }}

   Route::get('/search/', array(
    'as'    => 'name-search',
    'uses'  => 'ProductController@showSearchPage'
    ));

   Route::post('/search/', array(
    'as'    => 'name-search-post',
    'uses'  => 'ProductController@postUseSearch'
    ));

    public function postUseSearch(){

        $searchString = Input::get('keyword');

        $insert                         = new Searchword();
        $insert->keyword                = $searchString; // not saving into the database?

   more code...

   <?php

   use Illuminate\Auth\UserTrait;
   use Illuminate\Auth\UserInterface;
   use Illuminate\Auth\Reminders\RemindableTrait;
   use Illuminate\Auth\Reminders\RemindableInterface;

   class Searchword extends Eloquent implements UserInterface, RemindableInterface {

    protected $fillable = array (
        'keyword'
    );

    use UserTrait, RemindableTrait;

    /**
     * The database table used by the model.
     *
     * @var string
     */
    protected $table = 'searchword';

    /**
     * The attributes excluded from the model's JSON form.
     *
     * @var array
     */
    protected $hidden = array();

   }

   Database Schema 
   id (int) 
   keyword (varchar 255) 
   updated_at (datetime) 
   created_at (datetime)