Error when register

Who can help me:
Warning: Cannot modify header information - headers already sent by (output started at /home/thietkeecc/domains/thietkeecc.com/public_html/homes/catalog/language/vietnamese/affiliate/register.php:1) in /home/thietkeecc/domains/thietkeecc.com/public_html/homes/system/engine/controller.php on line 28Warning: Cannot modify header information - headers already sent by (output started at /home/thietkeecc/domains/thietkeecc.com/public_html/homes/catalog/language/vietnamese/affiliate/register.php:1) in /home/thietkeecc/domains/thietkeecc.com/public_html/homes/system/engine/controller.php on line 29

Make sure there is no white space after the closing php tag in catalog/language/vietnamese/affiliate/register.php
or remove the closing tag (it is not required)