Contact v2.05 beta

Fatal error: Uncaught Error: Call to undefined function imagecreate() in /var/www/dehaancompany/lib/classes/class.captcha.inc.php:10 Stack trace: #0 /var/www/dehaancompany/lib/classes/class.captcha.inc.php(59): captcha->captcha_generator('64?6MQ@E') #1 /var/www/dehaantjes/includes/makemail.inc.php(12): captcha->nieuwe_captcha() #2 /var/www/dehaantjes/includes/pages/contact2.inc.php(54): require_once('/var/www/dehaan...') #3 /var/www/dehaantjes/index.php(108): require_once('/var/www/dehaan...') #4 {main} thrown in /var/www/dehaancompany/lib/classes/class.captcha.inc.php on line 10