SAP Message VL656 - You must save before you can post goods issue (due to forecast)

Diagnosis
You have either created a new delivery item or changed the material,plant, material staging date, or quantity in the delivery item. You nowwant to post the goods issue.
In this situation, the system cannot reduce the planned independentrequirements properly.

System Response
The system does not post the goods issue.

Procedure
First choose 'Back' and then save the delivery. Then post the goodsissue.
The system then correctly reduces the planned independent requirementsas defined in Customizing.

594983Outbound deliv w/o order reference: incorr reqt reduction