Error when trying to mount .sqb

[swirl80]

I can mount a native sql backup (.bak) no problem but if i try to select one of our .sqb's in order to mount it, i get this:

"The media family on device X is incorrectly formed. SQL Server cannot process this media family.
RESTORE HEADERONLY is terminating abnormally"

From what i've read this error relates to Hyperbac service not running or it not being a supported backup file - which i believe it should be!!

The file is not corrupt because i can restore it via sql backup to another server.

any ideas??
SQL 2005 x86 SP3

[javen]

SQL Virtual Restore 2.0 supports only SQL Backup version 6 backup files, this particular backup file was from version 5. Reference from the product page:

“To mount the backup as a fully functional database, you just need to point SQL Virtual Restore at full, differential or transaction log backups created with SQL HyperBac, SQL Backup Pro (version 6), or native SQL Server.”