QBOv3 XML Validation Fault 2500 (Невалиден референтен идентификатор)

Опитвам се да създам тестова фактура в quickbooks с помощта на quickbooks-ruby gem. Забележка: Имам тестов акаунт в QB, който няма нищо: фактура, клиент и т.н. Това е нов акаунт, създаден само с цел тестване. И така, ето моят код:

service = Quickbooks::Service::Invoice.new
service.company_id = current_user.company_id
service.access_token = create_consumer

qb_invoice = Quickbooks::Model::Invoice.new
qb_invoice.customer_id = 123

line_item = Quickbooks::Model::InvoiceLineItem.new
line_item.amount = 100
line_item.sales_item! do |detail|
  detail.unit_price = 100
  detail.quantity = 1
  detail.item_id = 1
end

qb_invoice.line_items << line_item

res = service.create qb_invoice
p res.id #exception!

def create_consumer
  OAuth::AccessToken.new(.....)
end

Заявка:

   METHOD = post
   RESOURCE = https://qb.sbfinance.intuit.com/v3/company/fdsfdsfdsfds123/invoice

<?xml version="1.0" encoding="utf-8"?>
<Invoice xmlns="http://schema.intuit.com/finance/v3" sparse="false">
  <Line>
    <Amount>100.0</Amount>
    <DetailType>SalesItemLineDetail</DetailType>
    <SalesItemLineDetail>
    <ItemRef>1</ItemRef>
    <UnitPrice>100.0</UnitPrice>
    <RatePercent>0.0</RatePercent>
    <Qty>1.0</Qty>
    </SalesItemLineDetail>
  </Line>
  <CustomerRef>123</CustomerRef>
  <TotalAmt>0.0</TotalAmt>
  <Balance>0.0</Balance>
  <Deposit>0.0</Deposit>
</Invoice>

и отговор с грешка:

RESPONSE CODE = 400

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<IntuitResponse xmlns="http://schema.intuit.com/finance/v3" time="2014-03-06T19:30:49.168-08:00">
  <Fault type="ValidationFault">
    <Error code="2500" element="">
      <Message>Invalid Reference Id</Message>
      <Detail>Invalid Reference Id : Something you're trying to use has been deleted. Check the fields with accounts, customers, items, vendors or employees.
      </Detail>
    </Error>
  </Fault>
</IntuitResponse>

Може ли да е, защото клиент с id = 123 не съществува? Ако не, каква е причината тогава?