Avast U3 version does not recognize Sandisk USB drive

I formatted my Sandisk Cuzer Micro, wiping out everything. I then re-installed the launchpad and used it to download and install Avast. When I try to insert my license key Avast responds with a notice that the key is for a Sandisk USB drive and is invalid for my device. Any idea how I might convince Avast that it really is a Sandisk device?