Zend reCaptcha issue

Hi,

I am working out of chpt. 8 in David Power's new book Dreamweaver CS5 with PHP.

I am getting an error with the reCaptcha script WHEN THE PAGE LOADS:

Before adding the custom error message, I was getting "Missing response field" as an exception (again, as the page loaded - no form button clicked). From what I can tell, my code in 'process_comments.php' is identical to the book's:

I'm hoping perhaps Mr. Power's can help me decipher why this is happening.