I got it to work. Finally!
Here's what I did.
I deleted everything from the Lego Rockband off the hard drive (3 files)
I followed the deleted the License instructions as previously posted and then re-downloaded it.
Then I went into the hardrive under ROCKBAND and scrolled down until I found LegoRockband License and then copied the license to my 512KB backup drive.
I then went into Lego Rockband and went through all the settings (i didn't skip them).
I finally went into the Music Store, selected Export and it worked!
I hope this helps you.