Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, firstname.lastname@example.org
and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
This is not usual. There must be something restricted or broken on your server. Please ask your system administrator why it doesn't work, and why it gives you this server error. It's supposed to work, it's not an error of a PHP script.