laravel policy gves flalse - laravel

Question

I am new to laravel and now trying to learn policies so I created the following models:
class group extends Model
{
protected $fillable = [
'id','book_id',
];
/**
* The attributes that should be hidden for arrays.
*
* #var array
*/
protected $hidden = [
];
public function users(){
return $this->belongsToMany('BOOK_DONATION\User')->withPivot('last_seen_id');
}
}
and :
class User extends Authenticatable
{
use Notifiable;
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = [
'name', 'email','country','state/provience','city', 'token', 'password','postal_code',
];
/**
* The attributes that should be hidden for arrays.
*
* #var array
*/
protected $hidden = [
'password','verfied', 'remember_token',
];
public function Book(){
return $this->hasMany('App\Book');
}
public function groups(){
return $this->belongsToMAny('BOOK_DONATION\group')->withPivot('last_seen_id');
}
}
and :
class group_user extends Model
{
//
protected $table='group_user';
protected $fillable = [
'user_id','group_id','last_seen_id'
];
/**
* The attributes that should be hidden for arrays.
*
* #var array
*/
protected $hidden = [
];
}
now the group_user is model for the intermidate table required for the many to many relation between users and groups
and here is my policy:
class group_userPolicy
{
use HandlesAuthorization;
/**
* Determine whether the user can view the group_user.
*
* #param \BOOK_DONATION\User $user
* #param \BOOK_DONATION\group_user $groupUser
* #return mixed
*/
public function view(User $user, group_user $groupUser)
{
//
return in_array($user->id,$groupUser->user_id);
}
}
and here is the specific programming lines from controller related :
$grouUser=group_user::where('group_id',$group_id)->pluck('user_id');
if(Auth::user()->cant('joinChat',$grouUser)) return redirect('/sorry');
now I always get redirected to sorry page but I have the right yo join chat so what is wrong?