Undefined index when using other php variable as array key (Laravel)

my problem is that variable $this->country can not be inserted as key in array. Any one knows why ?

$array[Config::get('app.locale')][$this->country]; throws Undefined index $array[Config::get('app.locale')]['de']; throws no errors

Config::get('app.locale') var_dump string(2) "de"
$this->country            var_dump string(2) "de"




  array:1 [▼
        "de" => array:2 [▼
              "de" => "Germany"
              "us" => "USA"
        ]
  ]

via Chebli Mohamed