Logout problems – blank white screen

What version of phpBB are you using? phpBB 3.0.12
What is your board’s URL? it’s on my localhost. sorry.
Who do you host your board with? no one
How did you install your board? I have been downloaded it from the phpbb.com main site
What is the most recent action performed on your board? nothing. after installing wp-united it worked for couple of days and than the problem came out.
Is registration required to reproduce this issue? No
Do you have any MODs installed? Yes. wp-united that connected to my wordpress blog.
What styles do you currently have installed? prosilver, subsilver2 but the active one is Modestus by rocket team
What language(s) is your board currently using? English
Which database type/version are you using? MySQL 5.5.35
What is your level of experience? Very good at php and phpbb
When did your problem begin? I assume something screwed with wp-united
Please describe your problem:
when user try to logout from the system (from the forum and from the wordpress) he is redirected to logout:

http://95.175.32.60/forum/ucp.php?mode=logout&sid=65ffffa01091d6104ddd797a444cb29b

but he stay on this page, that have nothing. only blank white page.
after the user delete the rest of the url and go back to the forum/site hes no longer connected.

I’ve tryied to cahgne the cookie settings, and mad that check in severl computers and browsers and still nothing.
I’ve allso tryied to set the debug option on, and this is the error I get:

phpBB Debug] PHP Notice: in file [ROOT]/includes/auth/auth_wpbb.php on line 14: Undefined index: i
[phpBB Debug] PHP Notice: in file [ROOT]/includes/auth/auth_wpbb.php on line 14: Undefined index: mode

And this is the auth_wpbb.php file:
http://pastebin.com/X5bYuavi

Does someone have any idea what can I try next?