Generally a blank white page when you expect content is a PHP error.  As we offer production servers and not development servers we have "display_errors" off by default which is why you would get a blank white page instead of an error message.

You can turn on "display_errors" by adding the following line to a file called ".htaccess" in the same folder as the script having issues:
php_value display_errors on

If the file ".htaccess" does not exist, you are welcome to create one for this purpose.