Transaction on voucher do not balance as per date

Hi,

I'm trying to post a project credit note in AX 2012.  What I've done is, from the project I created a sales order with a negative qty.  I then created a new invoice proposal for the sales order.  When I go to post the invoice proposal, I receive the following messages in the InfoLog

• Project contract ID: EFM-001731
  • info - Voucher EFM-200000001, date 2/11/2013, account , transaction currency amount 999.00, accounting currency amount 999.00, reporting currency amount 999.00, currency ZAR, text
  • info - Voucher EFM-200000001, date 2/11/2013, account , transaction currency amount -1,138.86, accounting currency amount -1,138.86, reporting currency amount -1,138.86, currency ZAR, text
  • warning - The transactions on voucher EFM-200000001 do not balance as per 2/11/2013. (accounting currency: -139.86 - reporting currency: -139.86)
  • error - Posting has been cancelled.
• error - An error occurred during update

This only occurs when trying to post a sales order with a negative qty.

The invoice proposal posts just fine with a positive qty.

Your help is much appreciated.

Thank you,

Dylan