Might sound stupid, but have you been in the correct place ie. in the profiles definition?
From some documentation:
Quote:
- Select the LPAR and deactivate it.
- Go to Configuration -> Manage Profiles.
- Select the profile that needs to be activated.
- Go to Processors, change the Processor compatibility mode: to the required setting and boot it using the same profile.
There is some steps in it, that might help to identify the problem:
Verifying the processor compatibility mode of the mobile partition
Have no HMC at hand like Michael, sorry.