Get SalesPrice for specific Item and Customer

I want to find the SalesPrice for item that is in the SalesPrice Agreements for the customer.

I am trying this way:

priceDisc = new PriceDisc(ModuleInventPurchSales::Sales,

inventJournalTrans.ItemId,

inventJournalTrans.inventDim(),

inventJournalTrans.UnitId(),

systemdateget(),

inventJournalTrans.Qty,

custTable.AccountNum);

if (priceDisc.findPrice(custTable.PriceGroup))

price = priceDisc.price();

else if (priceDisc.findItemPrice())

price = priceDisc.price();

And I think that its not finding any price and returning default price for the item.