Wmi Permenet Event Handler not working = clues?

I am trying to get a permanent event hander to work - so far I fail.

I have two basic scripts - one that sets the handler and another one that is meant to run when the event occurs.

Here is the core of the event-handler :

# Group to monitor
$Group = 'UG-GAdmin'

#region Create the Event Filter
# Create the Event Filter
Write-Verbose -Message "*** Creating the Filter to Monitor Group $Group"            
$Q = "Select * FROM __InstanceModificationEvent `
      WITHIN 5 `
     WHERE TargetInstance ISA 'ds_group' AND TargetInstance.ds_name = '$Group'"
# Set parameters to call to New-CimInstance
$param = @{
           QueryLanguage =  'WQL'
           Query          =  $Q
           Name           =  "EventFilter1"
           EventNameSpace =  "root/directory/LDAP"
       }
# Now create the Instance Filter
   $InstanceFilter = New-CimInstance -ClassName __EventFilter -Namespace root/subscription -Property $param -Verbose
#endregion  
#region Create the Permanent Event Consumer details
$param =@{
          Name = "EventConsumer1"
          CommandLineTemplate="PowerShell.exe -File C:\test.ps1 -Group $group"
       }

$InstanceConsumer = New-CimInstance -Namespace root/subscription -ClassName CommandLineEventConsumer -Property $param -Verbose

#endregion 
#region create a binding between the Filter Filter and the consumer
$param = @{
          Filter = [ref]$InstanceFilter    
           Consumer=[ref]$InstanceConsumer
         }

$InstanceBinding= New-CimInstance -Namespace root/subscription -ClassName __FilterToConsumerBinding  -Property $param -Verbose 

#endregion