Goods Receipt with serial numbers

Hello everyone

I'm having problems when i try to add a goods receipt with serial numbers

Code:

        OReceipt = oCompany.GetBusinessObject(BoObjectTypes.oInventoryGenEntry)

        OReceipt.Series = 18

        OReceipt.DocDate = Date.Now

        OReceipt.TaxDate = Date.Now

        OReceipt.Lines.ItemCode = "MP.PP.241"

        OReceipt.Lines.Quantity = 1

        OReceipt.Lines.SerialNumbers.InternalSerialNumber = "SN-01"

        OReceipt.Lines.SerialNumbers.ManufacturerSerialNumber = "SN-01"

        OReceipt.Lines.AccountCode = "_SYS00000000109"

        OReceipt.Lines.WarehouseCode = "MPfabrik"

        OReceipt.Comments = ".NET"

        res = OReceipt.Add()

Any help will be greatly appreciated!