Segmentation "Valid From" date cannot be blank

What causes this issue?

You have entered a value in the field "ATP/MRP Status"
(SGT_MRP_ATP_STATUS) and have not maintained the segmentation "Valid
From" date.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Enter the segmentation "Valid From" date if you have maintained a value
in the field "ATP/MRP Status" (SGT_MRP_ATP_STATUS).

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.