MYOB API V2 Updating Applied Amount on Purchase Bills

Hi,

I'm using,

ItemBillService itemBillService = new ItemBillService(mcfvm._configurationLocal, null, mcfvm.MyOAuthKeyService);
PagedCollection<ItemBill> itemBills = itemBillService.GetRange(mcfvm.cf, paybillspageFilter, mcfvm.credentials, null);

To try and retrieve pay bills record, which is coming up with an empty result. I can see the record via the user interface in the myob application,

I can also retrieve it using,

var billSvc = new BillService(mcfvm._configurationLocal, null, mcfvm.MyOAuthKeyService);
PagedCollection<Bill> bills = billSvc.GetRange(mcfvm.cf, paybillspageFilter, mcfvm.credentials, null);

but when I use,

itemBillService.UpdateEx(mcfvm.cf, itemBill, mcfvm.credentials, ErrorLevel.WarningsAsErrors);

by coping bills object to itemBIll object, I receive the following error message,

"Amount:(PurchaseEvent)"

4457

"TransferEvent_VoidTransactionWarning"

Thank you.