Enter an order o r group

What causes this issue?

In order planning, you can either go into planning with a single order
or a whole group of orders. However, you cannot go in with both
simultaneously.

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?

Delete either the order or the group of orders, or
Enter a value in one of the fields.

Error message extract from SAP system. Copyright SAP SE.