SAP Note 17031 - ME21 w. ref. to pur. req.; pur. req. remains open

Symptom:

A purchase order is created with a reference to a purchase requisition. If you then branch to the schedule screen and distribute the quantity among several dates, the ordered quantity in the purchase requisition is only reduced by the amount from the first schedule line.

Cause and prerequisites

Handling error

Solution
If you want to distribute the quantity among several dates, and the reference to the purchase requisition should apply to all the dates, select function "Purchase order -> Create with ref. -> To pur. req." on the schedule screen. Otherwise, the reference to the purchase requisition will not be retained, and the open quantity of the purchase requisition will not be reduced like you want.
This, however, is not possible with purchase requisitions that were generated from a sales and distribution document. You can only copy those purchase requisitions into one single schedule line.

Additional key words

ME21, ME22, scheduled quantity, subset, purchase requisition,
purchase requisition reference