But i see that with your code right JS is called:

jw_sigpro/includes/js/jquery_colorbox/colorbox/jquery.colorbox-min.js

(Have to say that with version before 2.5 all popup engines worked. No conflicts at website)

Sorry Konstantin, it works now with your code. It was conflict with jQuery from xpertscroller module.
It means JS scripts from last SIG PRO versions are much changed. Because all of them worked before together with xpertscroller.

Need to fix that problem.

For all other reading this, Konstantin´s fix is right for problem with popup.

I am not sure i understand you. I use absolutely last SVN version of K2.

Anyway it works.  :)

Tell me just shortly, did you customized something in Lytebox files ?
A mean, can i use latest Lytebox v3.25 files ?

I overwrited them and don´t see some problems, but you sure know it better.