Signed MSP still says Unknown Publisher

[Thatcham]

Hi,

We create monthly updates for our software released as MSP files. While we
use Installshield 2008 to build the MSI installations, we use MSIMSP to build
the patches. The patches install without issue, however, we have an issue
signing it. Signtool says that the patch is signed successfully, but Vista
insists that it is an Unknown publisher. How do we fix this?

Also, while installing the MSI, it is happily acknowledging our signature,
but uninstall is not. It insists Unknown Publisher.

Thanks in advance