Exchange Web Services and Exchange 2010 SP3

All,

I have a script (a few scripts actually) that I'm trying to run in the Exchange Management Shell. We have Exchange 2010 SP3 on 2008 R2 server with SP1. I have downloaded and tried EWS API version 1.2 and 2.0. I keep getting a Bind error in various small scripts. ie

exception calling "Bind" with "2" argument(s): "The specified object was not found in the store."
At D:\development\powershell\sjemail2.ps1:34 char:66
+ $InboxFolder = [Microsoft.Exchange.WebServices.Data.Folder]::Bind <<<< ($service,$folderid)
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : DotNetMethodException

The relevant bits of code in each script are :

[Reflection.Assembly]::LoadFrom("C:\Program Files\Microsoft\Exchange\Web Services\2.0\Microsoft.Exchange.WebServices.dll")
$service =  New-Object Microsoft.Exchange.WebServices.Data.ExchangeService -ArgumentList([Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2010)

if ($credential -ne $null)
{    
      Write-Host "Credential OK"  
      $credential.GetNetworkCredential()
}
else  
{    
      Write-Host "Problem with Credential"  
      $service.UseDefaultCredentials = $true;
}    

function GetUnreadInboxMails([string] $emailAddress)  
{    
      Write-Host "In GetUnreadInboxMails"  
      Write-Host $emailaddress
      $service.AutodiscoverUrl($emailAddress, {$true});          
      $mailbox = New-Object Microsoft.Exchange.WebServices.Data.Mailbox($emailAddress)    
      Write-Host $mailbox
          $folderId = New-Object Microsoft.Exchange.WebServices.Data.FolderId([Microsoft.Exchange.WebServices.Data.WellKnownFolderName]::Inbox, $mailbox)      
      Write-Host $folderId      
      Write-Host "Before folder"      
      $folder = [Microsoft.Exchange.WebServices.Data.Folder]::Bind($service, $folderId);    
      Write-Host "After folder"      


I have double checked the EWS directory, which is OK. The error always happens at the line
$folder = [Microsoft.Exchange.WebServices.Data.Folder]::Bind($service, $folderId);  

I have read on some forums that this is an indication of access rights problems. We also have Exchange 2010 SP3 and was wondering which version of EWS I should be using and do I need to change the entry in the following code to reflect I'm using SP3 .....
$service =  New-Object Microsoft.Exchange.WebServices.Data.ExchangeService -ArgumentList([Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2010)



Thanks