Laravel 4.2 Migrate

public function up()
{
    Schema::create('users', function($table) {

        $table->increments('id');
        $table->unique('username', 10);
        $table->unique('email', 20);
        $table->unique('phone', 16);
        $table->string('password', 100);
        $table->string('password_temp', 100);
        $table->string('operation_password', 100);
        $table->string('operation_password_temp', 100);
        $table->integer('groupe_id', 1);
        $table->timestamps();

    });
}

не пойму из за чего эта ошибка

Syntax error or access violation: 1075 Incorrect table definition; there can be only one auto column and it must be defined as a key