Domain user issue setting up PerformancePoint Service App

I am following the Technet BI lab - http://technet.microsoft.com/en-us/library/hh223287(v=office.14).aspx

All going fine until I try and enter the unattended service account credentials into the PPT service app -  SecureStore and Unattended Service Account section:

I create a new AD account PPSunattended and I get this error

The account credentials for the Unattended Service Account are not valid. Verify the domain user name and password are correct and that the account is located in a Trusted Domain

I've reset the password, tried a few accounts and they all fail except the administrator account - so I can get it to work but this is not a valid configuration

Do I need to create a Target app ID in Secure store first? The lab doesn't mention it

SP2010 SP1 Enterprise with DC and SQL on same box

any ideas?

Cheers

jonj