弄清楚问题出在XML提要而不是代码:

Figured out the issue was with the XML feed rather than code:

XML feed缺少此行:

XML feed was missing this line:

<r25:events xmlns:r25="http://www.collegenet.com/r25" xmlns:xl="http://www.w3.org/1999/xlink" pubdate="2010-05-19T13:58:08-04:00">

不过感谢您的帮助.