miiskmu export: no access to the MIIS database

I am trying to export my encryption key for the ‘User Profile service’ application in SharePoint 2010 but I keep getting the following error: ‘The credentials do not have access to the MIIS database‘ no matter what I do.

The user I’m trying it with is called ‘SHAREPOINT\Administrator’ and is a farm administrator as well as a serveradmin in SQL Server. SharePoint, SQL Server and Active Directory are all installed on the same machine so it’s a pretty simple setup.

I’ve tried to export via the GUI and the command-line like this:

miiskmu.exe /e key /u:administrator@sharepoint.local * 

and returns the following output

Error: Object reference not set to an instance of an object.

Error Code: 80004003