"unable to create restore plan to break in the LSN chain" during exercise in book administering MS SQL Server 2012 databases

Hi,

Bought the MS book  "Administering MS SQL Server 2012 databases" and currently working in chapter 7 and its about mirroring. In one exercise you have to create a mirrored database. The first step is to to back up the databases. But these already giving troubles.....I've done the exercise three times and i'm keep getting the following error:  "Unable to create restore plan to break in the LSN chain".

These are the steps i'm taking:

1. Copy database wizard and copy Adventureworks2012 to Adventuremirror (A).
2. Set to full recovery mode (A).
3. Create a backup  (A).
4. copy to other server  (B).
5. Restore with No Recovery (B).
6. Create a transactional log backup (A).
7. Try to restore transactinal backup to other server (B). But the a yellow error message appears on top of the window : "Unable to create restore plan to break in the LSN chain."

It seems a bit odd as i'm following the steps of the book.

Greetz,

Hennie