Hi, I'm getting the same error and maybe someone can help.
I'm trying to prevent a default site-wide banner from showing up on specific category archives and single post pages by using this widget logic conditional tag:
!is_category(array(X,XX) || !is_single() && in_category(array(X,XX))
I have 2 other widgets that should take it's place, and they do work - as long as the default site-wide banner widget is removed completely.
Can anyone tell me if my above syntax is wrong?
Looking at alanft's response, I carefully checked all my sytax for any errant brackets but it looks ok. I'm a PHP newbie, so maybe the above code is wrong?
Any help appreciated.