Laravel force delete fails

I have a Role Model

class Role extends EntrustRole
{
//
public function permissions()
{
    return $this->belongsToMany('App\Permission', Config::get('entrust::permission_role_table'));
}
}

Now i would like to delete a certain role

$role = Role::where("display_name",'=', $request->route("role"))->first();
  $role->delete() //fails
  $role->forceDelete() //also fails

THe above returns an error

message www/html/laravel/keybrands/vendor/laravel/framework/
 src/Illuminate/Database/Eloquent/Concerns/HasRelationships.php"

 "Class name must be a valid object or a string"

THe permission model is in the App namespace .

Where could i be going wrong?

via Chebli Mohamed