How to add a Distribution Point to a Distribution Point Group

$DistributionPoint = 'Server'
$DomainName = 'CM.LOCAL'
$SiteCode = 'PS1'
$NALPath = "[""Display=\\" +  $DistributionPoint + "." + $DomainName + "\""]MSWNET:[""SMS_SITE=" + $SiteCode + """]\\" + $DistributionPoint + "." + $DomainName + "\"
$DPGroupQuery = Get-WmiObject -Namespace "Root\SMS\Site_$SiteCode" -Class SMS_DistributionPointGroup -Filter "Name='New Distribution Group'"
$DPGroupQuery.AddDistributionPoints($NALPath,$True)