Powershell remote access denied
You need to pass in the credential object (created with Get-Credential) using the "-Credential" switch.
See this MSDN article for more information and an example.
Chapter 13 (page 502) of Bruce Payette's (UTTERLY AWESOME) "Windows Powershell in Action, Second Edition" comprehensively covers configuration of remote Powershell admin. If you've not already asked Santa for a copy of this wonderful book, DO SO NOW! :)
In case you are in a hurry:
MSDN (and other sources) have some good documentation on how to
- Enable remoting to a remote server
- Connect from your local server to your remote server & execute commands
HTH.