SQL Statement on Access

Hello,
Iam trying to select the records from an Access table where the column -> factura(string) is equal to null so I do this
"Select * FORM ordenes WHERE factura = Null" and it doesnt work, but when I do this: <> Null it does bring the records that are not Null.

Can you Help me?
Thanks

change your query to
select * from tablename where columnname is null
this should return all rows where the columnname has a null value.