The you attach a database to SQL Server 2008 R2. The first error you hit is.
An error occurred when attaching a database(s).
When you click the hyper link you see the error as below.
The database ‘COMMERCE’ cannot be opened because it is version 706. This server supports version 661 and earlier. A downgrade path is not supported.
Could not open new database ‘COMMERCE’. CREATE DATABASE is aborted. (Microsoft SQL Server, Error: 948)
This is because your database is from SQL Server 2012. The only way to resolve this as I found is to Generate Script from SQL Server 2012 then run it in SQL Server 2008 R2.
The video below shows how to generate script from SQL Server 2012. Unfortunately the data you need to export them separately.