Cannot add more computers

Hi there,

i have got few computers in same local net. I can install Norton Family on first computer and everythink is okay, but if i want install this program on next PC (using same username), installation on first computer stop working and this computer disappear from my account. Also, I can have got only one device in my account, always just the last one installed. Every previous installations is mising and stop working.

Please, can you help me?