get invoice Number

Hello,

could anyone tell me how to get the created invoice number ?

I have :


SalesJournal salJourn = SDKInstanceManager.Instance.OpenSalesJournal();
salJourn.SelectTransType(TransactionType.Invoice); // invoice
salJourn.SetShipDate(salJourn.GetJournalDate());

//blah.....


if (salJourn.Post())
{

return salJourn.InvoiceNumber;
} else{

//blah.....

}

my invoice number is off by one  should get the salJourn.InvoiceNumber before the post ?

Thank you