find computers account with powershell v2 cause xp

hello guys ,

i want to find all inactives computers  for 3 months, i started my script with my powershell book :)

But i have message between $(Get-Date)).days ........

I dont know why , and i test the script whithout where cmdlet , i got the last connexion date but at 01/01/1601

i want to resolve the two problems and get the solution.

and i try to use dsquery computer -inactive 12 and i get the result but i want the lastlogon date without an error.

# Comptes d'ordinateurs inactivés
param ($NonConnecteDepuisNbJours=30)
[datetime]$date = '01/01/1601'

$objdomain = [ADSI]''
$objRecherche = New-Object System.DirectoryServices.DirectorySearcher($objdomain)
$requete = '(&(objectCategory=Computer)(name=*))'
$objRecherche.Filter=$requete
$comptes = $objRecherche.findall()

$comptes | Select-Object @{e={$_.properties.cn};n='Nom Commun'},
@{e={$date.AddTicks($($_.properties.lastlogontimestamp))};n='Dernière Connexion'}|
Where-Object {(New-TimeSpan $_."Dernière Connexion"
$(Get-Date)).days -ge $NonConnecteDepuisNbJours
}

But