在提供的Eloquent模型上，您提供的关系字段不是有效的关系方法名称

我有两个表：选项和选项选择。以下是型号：

use LaravelBook'Ardent'Ardent;
class Option extends Ardent
{
    /**
     * The database table used by the model.
     *
     * @var string
     */
    protected $table = 'options';
    // MASS ASSIGNMENT -------------------------------------------------------
    // define which attributes are mass assignable (for security)
    // we only want these 1 attribute able to be filled
    protected $fillable = array('name');    
    public function selections()
    {
        return $this->hasMany('optionselection');       
    }
}
use LaravelBook'Ardent'Ardent;
class Optionselection extends Ardent
{
    /**
     * The database table used by the model.
     *
     * @var string
     */
    protected $table = 'option_selections';
    // MASS ASSIGNMENT -------------------------------------------------------
    // define which attributes are mass assignable (for security)
    // we only want these 1 attribute able to be filled
    protected $fillable = array('option_id', 'name');   
    public function choice()
    {
        $this->belongsTo('option');
    }
}

我正试图在Laravel管理员中创建关系，就像我以前做过很多次一样，但我不明白为什么会出现错误：您为选项选择提供的"选择"关系字段在提供的Eloquent模型上不是有效的关系方法名

    return array(
     /**
     * Model title
     *
     * @type string
     */
    'title' => 'Option Selections',
    /**
     * The singular name of your model
     *
     * @type string
     */
    'single' => 'Option Selection', 
    /**
     * The class name of the Eloquent model that this config represents
     *
     * @type string
     */
    'model' => 'optionselection',
    /**
     * The columns array
     *
     * @type array
     */
    'columns' => array(     
        'choice' => array(
            'title' => 'Option',
            'relationship' => 'choice',
            'select' => 'name',         
        ),
        'selection' => array(
            'title' => 'Selection'
        ),
    ),
    'edit_fields' => array(
        'choice' => array(
            'title' => 'Option',
            'type' => 'relationship',
            'name_field' => 'name', 
        ),      
        'name' => array(
            'title' => 'Selection Name',
            'limit' => 30,
        ),
    ), 
    'action_permissions'=> array(
    ),
 )

我知道方法/关系字段实际上确实存在，并且在Laravel Administrator之外得到了认可，因为这是有效的：

    $optsel = new Optionselection();
    // var_dump($svcloc);
    if (method_exists($optsel, "choice")) {
        echo '<br/>Recognizes!';
    } else {
        echo '<br/>Problem!';
    }

为什么我会出错？