Error 0006:0906 on Panda Internet Security 2012 Licenses

I purchased three Panda Internet Security 2012 licenses. I will be using the first two licenses on my desktop PC and laptop.
The third license is for my desktop PC at work. But I got an “Error 0006:0906, the limit of activations of your product has been exceeded.
Why could it be when I just bought three licenses?
Anyone help me please.
