ZF-5796: Wrong date format, wrong interpreted by twitter
The current $_dateFormat (line 58 of Zend/Service/Twitter.php) value isn't correctly interprated by twitter. It often leads to empty responses when there has to be new tweeds.
I would therefore strongly suggest to use the same format as twitter uses itself in the responses:
Mon Feb 16 13:44:39 +0000 2009
$_dateFormat = 'D M d H:i:s O Y';