set-aduser zip code for bulk users

i try to update the zip-code for active directory users as the below 

# Import AD Module             
Import-Module ActiveDirectory 
$users = Import-Csv -Path C:\zip.csv
# Loop through CSV and update users if the exist in CVS file            
foreach ($user in $users) {
Get-ADUser -Filter "SamAccountName -eq '$($user.Username)'" 
Set-ADUser -PostalCode $($user.zipcode)
}

Ahmed Zidan Network Administrator