I am trying to upgrade the IOS of a 2955 using Cisco Network Assistant 5.5. I am replacing c2955-i6q4l2-mz.121-22.EA12.bin with c2955-i6k2l2q4-tar.121-22.EA13.tar. I have done this before, but for some odd reason now the the upgrade keeps failing. I'm not given any reason, just that the upgrade fails. Does anyone know how to upgrade it from command line correctly or why the upgrade is failing. Thanks for any assistance that can be given.