Error while restore SharePoint from back-up

I got the following error while restore SharePoint (2007) Site from a back up

Object ... failed in event OnRestore. For more information, see the error
log located in the backup directory. SqlException: The media family on device
'...\spbr0000\0000000B.bak' is incorrectly formed. SQL Server cannot process
this media family. RESTORE DATABASE is terminating abnormally.

The restore log file got this message

Error: Object ... failed in event OnRestore. For more information, see the
error log located in the backup directory.
SqlException: The media family on
device '...\spbr0000\0000000B.bak' is incorrectly formed. SQL Server cannot
process this media family.
RESTORE DATABASE is terminating abnormally.

I scratched my head several times, wondering if my SharePoint got problem? Well, the problem is odd enough: the back up was created on a SharePoint with SQL 2008; my target SharePoint is using SQL 2005.
This is a famous message when you restore an back up in newer SQL version into older SQL version. The backup or detach database file is not backward compatiple. Note: The SharePoint backup pacakage was created using SharePoint back up feature (Central Admin > Operations > Backup and Restore :: Perform a Back up)