Target stock should be zero

What causes this issue?

The <DS:DE.WRNGRCT>Only include goods issues</> indicator has been
selected. The simplified method of replenishment is therefore used. The
starting stock of the customer is used as the target stock level. Since
this is not know to the system, it is represented by a zero.

System Response

The line is displayed for you to correct.

How to fix this error?

Either deselect the Only include goods issues indicator and use the
Materials Management-based Inventory Management as the method of
replenishment, or enter zero as the target stock.

Error message extract from SAP system. Copyright SAP SE.