Main language file?

[eluser]InsiteFX[/eluser]
Do not use filename_lang create your own filename but it has to end with _lang.php and be in the language/
directory like application/language/english/file_lang.php

Code:

$lang['language_key'] = "The actual message to be shown";

// to use autoload or load it!
$this->lang->load('filename', 'language');

// to use
$tmp = $this->lang->line('language_key');
echo $tmp;

Did you read the CodeIgniter User Guide - Language Class?

InsiteFX