get-process returns incorrect sessionid when running over the network

I faced a strange problem. If I run the following statement everything is working fine.

Get-Process | Format-Table ProcessName, SessionId

Now I am just adding -computername parameter as follows.

Get-Process -computername localhost | Format-Table ProcessName, SessionId

I am getting a list of processes but all sessionids are 0 which is incorrect. The same is happening if I am trying to get a list of processes from a remote computer.

Did anyone see such a problem?

My OS is Windows 7.