Insert 0, anyway it'll be assigned by SQL Server.

Insert into Invoices (INVOICENO, Amount) Values (0, Amount)
IF NOT TABLEUPDATE()
  * Error
ENDIF
* Get new record with Identity value from backend
IF REQUERY() = 0
  * Error
ENDIF

>Sergey,
>
>Example: Insert into Invoices (Amount) Values (Amount)
>
>Error: Field INVOICENO does not accept null values.
>