problem restoring a backup

I have a backup file (xxxx.bak) in my c:\trmp directory.

When I launch SSMS signed on as "sa" and try to restore this database, i get this window:

 I am not able to enter anything for "Database" and the dropdown is empty.

Then if I switch it to "Device" I get this window:

Now, under "Destination" I am able to enter a database name, i.e. the name I want the database to be referred to after I restore it.

However, note the message at the top of the window: No backupset selected to be restored.

How do I resolve this issue?

Murray