I have a script to create PDF files, with PDFLib (I think so: have the functions PDF_new, PDF_open_file, …).
The script run very well in my computer (PHP 5.3.1), but in on-line server (PHP 5.2.14) the page appear white.
What is wrong? What I have to do?
Thanks.
Check the error log of apache. A white page suggests a fatal error, with “display errors” set to “off”, for security reasons.
perhaps turn on error reporting in php.ini to see what’s wrong 
it could be that on the production server, error reporting is turned off
Have a look on your server for a file called something like “php_error.log”. Is any error logged there?