php array undefined index, but everything is declared -

i've got problem going on:

intercepted error    undefined index: en    code:		8  line:		417

code piece one

$page_change_langs = array(  		'de' => '',  		'en' => '',  	);

code piece two

$tpl->assign('page_change_lang_de', $page_change_langs['de']);  	$tpl->assign('page_change_lang_en', $page_change_langs['en']);

i have no idea why getting error. index seems there.

complete code: http://pastebin.com/7xzyqgrq