Powershell script fails to return some environment variables

We have a simple support Powershell script that pulls several environment variables and displays them to the user.  When we run the script directly, it works.  When its launched as a RES application (10.1.100.0), some of the variables do not get displayed.

here is a snippit of the script.

     Physical  Computer Name: $ENV:ViewClient_Machine_Name

     Virtual Computer Name: $ENV:ComputerName

     Logged on as: $ENV:Username

     Virtual Computer IP:  $IP

     VMware Pool: $ENV:ViewClient_Launch_ID

The virtual computer name, logged on as,  and virtual computer IP show up.

The physical computer name, VMware pool do not show up.

Why does RES selectively decide which environment variables its going to return?  How do I correct this?

Thanks all.

-JCK