powershell - how to auto add and remove dhcp reservation with csv - csv

Question

my client.csv format is:
ScopeId,Name,ClientId,Ipaddress
10.10.10.0,Computer1,1a-1b-1c-1d-1e-1f,10.10.10.10
10.10.10.0,Computer2,2a-2b-2c-2d-2e-2f,10.10.10.11
10.10.10.0,Computer3,3a-3b-3c-3d-3e-3f,10.10.10.12
my client.csv format (when the user's ClientID is null):
ScopeId,Name,ClientId,Ipaddress
10.10.10.0,Computer1,1a-1b-1c-1d-1e-1f,10.10.10.10
10.10.10.0,Computer2,2a-2b-2c-2d-2e-2f,10.10.10.11
10.10.10.0,Computer3,,10.10.10.12
and then run my powershell with my csv,auto add dhcp server reservations is successful,but when the user's ClientID is null ,powershell could not auto remove dhcp server rereservations,my powershell script has some problem?
$ComputerName="WIN-OO4RE715BV8.test.com"
if (!$args) {
Write-Host "client.csv"
}
ELSE
{
$dhcpdata=Import-CSV $args
foreach ($dhcp in $dhcpdata){
$ScopeId=$dhcp.ScopeId
$Name=$dhcp.Name
$ClientId=$dhcp.ClientId
$IPAddress=$dhcp.IPAddress
if ($ClientId -eq $null) {
Remove-DhcpServerv4Reservation -ScopeId $ScopeId -Name $Name -ClientId $ClientId -IPAddress $IPAddress
}
Add-DhcpServerv4Reservation -ScopeId $ScopeId -Name $Name -ClientId $ClientId -IPAddress $IPAddress
}
}

Answer 1

$ComputerName="WIN-JA5I029SJFM.test.com"
if(!$args){
Write-Host "client.csv"
}
ELSE
{
$dhcpdata=Import-CSV $args
foreach ($dhcp in $dhcpdata){
$ScopeId=$dhcp.ScopeId
$Name=$dhcp.Name
$ClientId=$dhcp.ClientId
$IPAddress=$dhcp.IPAddress
Add-DhcpServerv4Reservation -ScopeId $ScopeId -Name $Name -ClientId $ClientId -
IPAddress $IPAddress
if(!$ClientId)
{
echo Remove-DhcpServerv4Reservation -ComputerName "$ComputerName" -IPAddress
$IPAddress
Remove-DhcpServerv4Reservation -ComputerName "$ComputerName" -IPAddress
$IPAddress
}
}
}