title: Quickbooks: Adding a negative value to an invoice using the QBDSK
body: <p>Is there any way to add a line item containing a negative amount to an existing invoice?</p>
  
  <p>I'm using QBSDK7 and QB Enterprise.  (and if it matters .Net 3.5)</p>
  
  <p>What we're attempting to do is automate the way we're creating invoices. We're already pulling in employee's time and applying it to the correct invoices, but when we go to add credits (just a negative amount on a line item on the invoice) using</p>
  
  <pre><code>InvoiceLineMod.Amount.SetValue(-1234)
  </code></pre>
  
  <p>it fails with the error "Transaction must be positive"</p>
  
  <p>I've also tried adding a Service Item with a negative amount and giving it a positive quantity and I get the same result.</p>
  
  <p>This seems like such a no-brainer as we have been doing this manually for the last 10 years. I'm guessing there is artificial restriction on this.</p>
  
  <p>Some things to consider:
  Credit Memos are no good as we need to display exact details of the reduction on the same page.</p>
  
  <p>We don't have payments to apply yet in most cases.</p>
  
  <p>This need to be done before any retainers are applied.</p>
  
  <p>Any help would be greatly appreciated. </p>