Hello. I had the old siggen and today i decided to install the last version.
I erased the BD and the siggen folder for don't have problems, but, i just finish to install the siggen and i have the next warnings.

Warning: Cannot modify header information - headers already sent by (output started at /home/www/hdtyrandes.awardspace.com/roster/addons/siggen/localization.php:1) in /home/www/hdtyrandes.awardspace.com/roster/addons/siggen/index.php on line 149

Warning: Cannot modify header information - headers already sent by (output started at /home/www/hdtyrandes.awardspace.com/roster/addons/siggen/localization.php:1) in /home/www/hdtyrandes.awardspace.com/roster/addons/siggen/index.php on line 156

Do you know what can be happening?.

Did you edit addons/siggen/localization.php?
If so, re-extract from the zip file and re-upload to your server