problem to add access to RSA key container

Question

I have two administrator users on my machine. With the first one I am creating a machine level key:

aspnet_regiis -pc "NetFrameworkConfigurationKey" -exp

and I see it created in "C:\Documents and Settings\All Users\Application Data\Microsoft\Crypto\RSA\MachineKeys".

Now I am trying to add access privileges with the second one:

"c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe" -pa NetFrameworkConfigurationKey "XXX" Adding ACL for access to the RSA Key container... The RSA key container was not found. Failed!

Am I doing something wrong?