If it's unable to load the language and you've copied them over as you say, then this is going to be a config issue. Ensure your path is exactly as it should be. A good way to do this is to create a file such as error.php
in your root website folder. Then put some erroneous code in it like
<?php
dfs sdf sd;
Then call the file at www.yoursite.com/error.php
, and it will show you the path in the error which you can copy exactly. One other unlikely but possible problem could be permissions, but the former is far more likely