[ Closed ] Issue with extern.php

I had an issue calling extern.php?action=online and action=online_full. I get the following error:

Notice: Undefined index: Guests online in /home/projecto/public_html/forum/extern.php on line 499
: 6

Notice: Undefined index: Users online in /home/projecto/public_html/forum/extern.php on line 504
: 1

(or line 502 in the second row for online_full value; usernames and the online user counts are properly displayed)

I'm not good in php. When I check those lines, the code there goes like this:

499:
    echo $lang_index['Guests online'].': '.forum_number_format($num_guests).'<br />'."\n";

502:
        echo $lang_index['Users online'].': '.implode(', ', $users).'<br />'."\n";

504:
        echo $lang_index['Users online'].': '.forum_number_format($num_users).'<br />'."\n";

My guess was that this is something about the entries in the language files for 'Guests online' and 'Users online'. However, I wasn't able to find a file in the lang folder holding those.

Then I realized I can check this on any PunBB installation and it is indeed valid here too:

http://punbb.informer.com/forums/extern … nline_full

I would be glad if you look into this, but also if you can point me on a quick fix. Will adding those entries in common.php in the lang folder do the job?

Thanks