Laravel migration cannot add foreign key

When i try to add foreign keys to my migrations the method 'foreign' is not known, when i try to run the migration i get an error saying something about a syntax error. i can't find what needs to be done.

SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ')' at line 1 (SQL: alter table requests add constraint requests_family_id_foreign foreign key (family_id) references id ())

this is my migration code

<?php

use Illuminate\Database\Migrations\Migration;

class TableFamilymembersKeys extends Migration
{
 public function up()
 {
    Schema::table('requests', function ($table) {
        $table->foreign('family_id')->reference('families')->on('id');
    });
 }
public function down()
 {

 }
}

does anyone know how to fix this or did someone encountered this problem before?

via Chebli Mohamed