Hi tester!
There is an hidden option:
-C, --no-cow
this because cowpatty seems to having trouble with parsing capture files
with multiple WPA handshakes.

That's all folks!
Happy Hacking! ;D

ah! ( the usual ballshit )
this software is write for testing the security of your password and WPA keys,
don't use it on hash and/or WPA handshakes of other people/company.