Process Pupil

Error running NWAdmin.exe -o DelegateAllTasks

I am trying to use the NWAdmin.exe to delegate all tasks from one user to another within a site. No matter what I do I get the same error:

Command line execution error: Server was unable to process request. ---> Attempt
ed to perform an unauthorized operation.

I did it as myself with farm admin permission, site collection admin and site admin and I also tried it as a Farm account.

Any idea what I am missing here? What permissions do I need to execute this command?