Run a Powershell Script from and AutoCAD shell

I'm new to Powershell and i'm trying to run a powershell script from a batch file.  The batch file is created with LISP in AutoCAD and invoked using the AutoCAD SHELL command.  It's really simple:

POWERSHELL & 'E:\tmp\Power Shell\My Scripts\WP.PS1'

The script is supposed to open a specific text file in wordpad, but it seems that execution halts right after Powershell is invoked.  If I enter the arguments into the resulting command window it runs.  How can I get this thing to run without having to enter data the second time?

Thank you,

J Leavitt