Undefined index: list_additional_groups

[TiPsY]

Greetings people,
I've recently noticed on my error log page that I have one and only error but happens alot.
I mean a really lot. There are 591 pages of it, 8861 same error messages in total

Here's what it says:

8: Undefined index: list_additional_groups

File: /home/*******/public_html/*********/forum/Sources/Load.php

Here's the line that is highlighted by the error message:

==>1335: 'list_additional_groups' => $profile['list_additional_groups'],

Any info of what's wrong?

[TheListener]

Which mods are installed on your forum?

[TiPsY]

Edit: Found the error, it was inside a package!