accessing remote wmi - security problem

Hi,

I am in the role of a client admin. I can access normal parts of a remote wmi using get-WMIobject without any problems. But now I want to access a different namespace with this command:

$namespace = "root\cimv2\Security\MicrosoftTPM"
Get-WmiObject -class Win32_TPM -computername $pcname -namespace $namespace -Authentication PacketPrivacy

As long as I access the local wmi-object it works without any problems. When I try to access a remote system, I receive an "access denied" error until I set "-Authentication PacketPrivacy".

Now I receive no more error messages but I still don't receive the tpm information from the remote system.

We use Win7 and Powershell 3 without powershell remoting.

Any ideas?

Sven