Add-PnPListItem not insert record if date field is null

Hi,

I am trying to add some reocord to a sharepoint list.

My source is SQL server and I have some record with a date filled and some others with a date null value.

My code is this:

Add-PnPListItem -List $ListName -Values @{

"Title" = $result.GetValue(0)
"Customer"=$result.GetValue(1)
"Address" = $result.GetValue(2)
"Description" = if($result.GetValue(4)){$result.GetValue(4)} Else {''}
"StopDate" = if($result.GetValue(3)){$result.GetValue(3)} Else {$null}

} -ErrorAction SilentlyContinue # 

I did some tests:

1) without testing the null value of the date, the record is not inserted
2) by testing the value first I tried entering
Else {$null}
Else {''}
Else {''}
Else {}

and in all cases the record is not inserted.

Where am I going wrong?
Thank you