I am trying to use Stanford POS Tagger in NLTK but I am not able to run the example code given here http://www.nltk.org/api/nltk.tag.html#module-nltk.tag.stanford
Note : Just posting it as answer to help in case others face this issue in future
I finally found out what I did wrong.. it turned out to be a blunder.
Tagger file name is not 'english-bidirectional-distim.tagger' but 'english-bidirectional-distsim.tagger'.