无法在控制器中加载模型

Since a couple of days I can't load a model in a codeigniter system anymore.

It gives the following error:

A PHP Error was encountered

Severity: Notice

Message: Undefined property: Clients::$mdl_clients

Filename: controllers/clients.php

Line Number: 48

Controller code:

private function GetAllClients()
    {
        $this->load->model('clients_model', 'mdl_clients');

        $clients = $this->mdl_clients->getClients()->result_array();
        return $clients;
    }

I read the codeigniter documentation again, and I'am not doing anything wrong that I'am aware of.. Can you guys help me out?

It was a weird issue with my server. I uploaded everything to another, and it worked again

Change the model name by 'clients_model.php' if you dont have, and your class most name 'Clients_model'