RSS problem

Hello,

since I installed the Inove theme, my RSS feed has gone down, I get an error message saying “

Warning: Cannot modify header information – headers already sent by (output started at /customers/askatasuna.be/askatasuna.be/httpd.www/index.php:15) in /customers/askatasuna.be/askatasuna.be/httpd.www/wp-includes/pluggable.php on line 865

“
I figured out that it should be a problem of a php file with a line break before the <?php or a line break after the last ?> but I have no clue on which file it should be. i checked several but no sign of it…

Thank you for any suggestions!