Result is not Displayed

[prihantoro2001 at gmail.com]

Dear all, 

i am new to Python and have this problem

=====
import nltk
puzzle_letters = nltk.FreqDist('egivrvonl')
obligatory = 'r'
wordlist = nltk.corpus.words.words()
[w for w in wordlist if len(w) >= 6
and obligatory in w
and nltk.FreqDist(w) <= puzzle_letters]
print puzzle_letters
======

this gives me <FreqDist with 8 samples and 9 outcomes>
while the expected outcome is ['glover', 'govern', ...]
did i miss something?

Thank you

Pri