Powershell v2 remoting – How to enable unecrypted traffic

I'm writing a powershell v2 script that I'd like to run against a remote server. When I run it, I get the error :

Connecting to remote server failed
with the following error message : The
WinRM client cannot process the
request. Unencrypted traffic is
currently disabled in the client
configuration. Change the client
configurati on and try the request
again. For more information, see the
about_ Remote_Troubleshooting Help
topic.

I looked at the online help for about _ Remote_Troubleshooting, but it didn't point me towards how to enable unecrypted traffic. Below is the script that I'm using that is causing me problems.

Note: I have already run Enable-PSRemoting on the remote machine to allow it to accept incoming requests.
I have tried to use a session option variable, but it doesn't seem to make any difference.

$key = "HKLM:\SOFTWARE\Microsoft\PowerShell\1\ShellIds"
Set-ItemProperty $key ConsolePrompting True

$tvar = "password"
$password = ConvertTo-SecureString -string $tvar -asPlainText –force
$username="domain\username"
$mySessionOption = New-PSSessionOption -NoEncryption 
$credential = New-Object System.Management.Automation.PSCredential($username,$password)

invoke-command -filepath C:\scripts\RemoteScript.ps1  -sessionoption $mySessionOption -authentication digest -credential $credential -computername RemoteServer

How do I enable unencrypted traffic?