White Screen when downloading PDF

When I try to download a PDF I get this error. I'm running all current version of all the necessary modules. It shows a blank white screen when trying to download the pdf. please help!
"[Thu Apr 24 14:05:21 2014] [error] [client 192.168.0.144] PHP Warning: POST Content-Length of 14558394 bytes exceeds the limit of 8388608 bytes in Unknown on line 0, referer: http://192.168.0.12/?q=admin%2Fmodules%2Finstall&render=overlay
[Thu Apr 24 14:06:54 2014] [error] [client 192.168.0.144] PHP Fatal error: Call to a member function setHeaderFont() on a non-object in /var/www/sites/all/modules/webform2pdf/webform2pdf.module on line 356, referer: http://192.168.0.12/?q=node%2F1%2Fwebform-results%2Fdownloadpdf&render=o...
[Thu Apr 24 14:06:59 2014] [error] [client 192.168.0.144] PHP Fatal error: Call to a member function setHeaderFont() on a non-object in /var/www/sites/all/modules/webform2pdf/webform2pdf.module on line 356, referer: http://192.168.0.12/?q=node%2F1%2Fwebform-results%2Fdownloadpdf&
[Thu Apr 24 14:06:59 2014] [error] [client 192.168.0.144] File does not exist: /var/www/favicon.ico
[Thu Apr 24 14:06:59 2014] [error] [client 192.168.0.144] File does not exist: /var/www/favicon.ico