PHP extends namespace\class unknown error - php

Question

This is my parent class code: \core\controller\controlmaster
<?php
namespace core\controller;
class controlmaster{
private $model_base = null;
//public function __construct(){
//always start session for any loaded controller
//session_start();
//}
public function _loadModels($models){
$file = dirname(dirname(__DIR__)).DIRECTORY_SEPARATOR.$this->model_base.$models.".php";
$file_alloc = str_replace("\\","/",$file);
if(file_exists($file_alloc)){
require($file_alloc);
$models_name = $this->model_base.$models;
return new $models_name();
}
}
public static function _setModelBase($model_location){
$this->model_base = $model_location;
}
}
?>
and this is my controller page for application : \applications\controller\index
<?php
namespace applications\controllers;
use core\configuration\configloader as config;
class index extends \core\controller\controlmaster{
public $config;
public function __construct(){
$this->config = new config;
$this->config->_parsePHP("j3mp_setting.php");
parent::_setModelBase($this->config->settings['app_model_base']); // Error doesn't appear when i comment this function
echo "This is main page and this is config for model app base : {$this->config->settings['base_url']}";
}
}
?>
This is core\configuration\configloader:
<?php
namespace core\configuration;
class configloader{
//Contains setting informations
public $inisettings;
public $settings;
public function _parseINI($file,$section){
$section = empty($section) ? false : true;
$file = __DIR__.DIRECTORY_SEPARATOR.$file;
if(file_exists($file)){
$parse = parse_ini_file($file,$section);
$this->inisettings = $parse;
}else{
throw new core\errorhandler\exception("File {$file} is not found in our system. Please contact administrator for details.","configloader");
}
}
public function _parsePHP($file){
$file = __DIR__.DIRECTORY_SEPARATOR.$file;
if(file_exists($file)){
$settings = array();
include($file);
$this->settings = $settings;
}else{
throw new core\errorhandler\exception("File {$file} is not found in our system. Please contact administrator for details.","configloader");
}
}
}
?>
When i comment "parent::_setModelBase(...)" code, the error disappear and the browser successfully print "This is main page and this is config for model app base : http://iosv3.net/". I think the error come from \core\controller\controlmaster, but I don't know how to fix that? I always try to edit the file (\core\controller\controlmaster) but notting happens... If error occured, the message ("This is main page ...") doesn't come out... Could you show me where is the error come from? Thanks...