feedparser error

[tad na]

python 2.7.2

The following code has an error and I can not figure out why:

import feedparser
d = feedparser.parse('http://bl.ocks.org/mbostock.rss')
numb = len(d['entries'])
for post in d.entries:
    print post.pubDate+"\n"

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the error is :

    print post.pubDate+"\n"
  File "build\bdist.win32\egg\feedparser.py", line 416, in __getattr__
    raise AttributeError, "object has no attribute '%s'" % key
AttributeError: object has no attribute 'pubDate'

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The only thing I can think of is feedparser does not like uppercase(pubDate)?????
I can not change someone else's rss.   What can I do here?