Norton Password Manager file (.NPM)

I am trying to import a Norton Password Manager file (.NPM) into Norton Internet Security 2011's Identity Safe.  The NIS 2011 installation is on a reformatted hard drive with a new clean reinstallation of Windows 7 Home Premium.  I backed up the old file before reformatting and reloading Windows.  It created a .NPM file but when I try to import it, I am not having any luck. It first asks for a password which I DID NOT create when I backed it up and then is says the file may be corrupted which doesn’t seem possible.  Please help.