RuntimeException when load model in another modules - HMVC

I have a new problem with Codeigniter HMVC when deploy my project to hosting Unix (it works well on localhost)

Code:

$this->load->model('User_management/Muser_management');

When I call Muser_management model file in User_profile controllers it throws an error:

Type: RuntimeException Message: Unable to locate the model you have specified: Muser_management

My structure

Code:

>root
 >application
    >modules

      >User_management
         >controllers
            User_management.php  
         >models
            Muser_management.php

      >User_profile
         >controllers
            User_profile.php  ->>call Muser_management model error
         >models
            Muser_profile.php

My Muser_mangement.php file:

Code:

<?php
   defined('BASEPATH') or exit('No direct script access allowed');

   class Muser_management extends MY_Model{

       public function get_listuser()
       {  
           $this->db->select('id,label,email,role');
           $user=$this->db->get('user');
           return $user->result();
       }
}
?>

Please help, thanks

This may not help at all, but try changing

PHP Code:

$this->load->model('User_management/Muser_management'); 


to

PHP Code:

$this->load->model('user_management/muser_management'); 


Paul.

PS Also, not sure if this will make any difference (or even if it is important) but models do not need the closing php tag.( ?> ) If you have a trailing white space that might cause problems too (or so I have been led to believe although I am not sure I completely understand why).