PROBLEM Errors with plugin

[thesneaker]

Hello!

I've GetSimple 3.3.15 installed with (not only) I18N plugin and Online Visitors plugin - all in up to date version.
Everything went fine until i simply changed my provider and now using another webspace with all necessary stuff
enabled.
When i now try to login as admin and then redirected to pages.php from I18N plugin i just see a white page.
After turning on debug mode i see those errors:

Warning: Cannot modify header information - headers already sent by (output started at /www/htdocs/******/****.de/plugins/online_visitors.php:1) in /www/htdocs/[b]******/****.de/admin/inc/cookie_functions.php[/b] on line 23

Warning: Cannot modify header information - headers already sent by (output started at /www/htdocs/******/****.de/plugins/online_visitors.php:1) in /www/htdocs/******/****.de/admin/inc/cookie_functions.php on line 23

Warning: Cannot modify header information - headers already sent by (output started at /www/htdocs/******/****.de/plugins/online_visitors.php:1) in /www/htdocs/[b]******/****.de/plugins/i18n_base/backend.class.php[/b] on line 7

So i disabled Online Visitors plugin and the error is gone. What to do here? I want to use it and what can be the cause just because the change of the webspace?
Sorry for those questions but i'm not this professional and maybe someone can help me?

THX!!!

[shawn_a]

Any errors? You can probably just turn of debugging

[thesneaker]

When i turn off debugging i just see a white page again - what does this help?
And yes, i have errors, you see them in the first post...

[shawn_a]

Check your error log for errors, not warnings

[datiswous]

check /path/to/getsimple/data/other/logs/errorlog.txt for errors

source: http://get-simple.info/wiki/debugging