Hi My name is Joan Manuel, I have Phpnuke 6.5, the Theme Helius, when i make clic on Forums i get this warning

Can Someone Help Me?

Warning: Cannot add header information - headers already sent by (output started at /home/webcindario/elprogramador/themes/Helius/theme.php:121) in /home/webcindario/elprogramador/includes/sessions.php on line 222

Warning: Cannot add header information - headers already sent by (output started at /home/webcindario/elprogramador/themes/Helius/theme.php:121) in /home/webcindario/elprogramador/includes/sessions.php on line 223