Redirect function not working in the different server

[eluser]y0rkez[/eluser]
Hello, I'm newbie using CI framework, I've finished working my first CI framework project, but I have a problem on redirecting URL, example for login authorization.
I've run my application on my server and it's done, but when I run on another server it has a problem with the following error:

A PHP Error was encountered

Severity: Warning

Message: Cannot modify header information - headers already sent by (output started at /home/sloki/user/h26319/sites/blabla.com/www/system/libraries/Exceptions.php:164)

Filename: helpers/url_helper.php

Line Number: 541

I don't understand what its mean, does anybody has solution?