Enter a business entity or a group

What causes this issue?

In real estate planning for business entities, you can enter either one
business entity or a group of business entities on the planning initial
screen. You cannot enter both.

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 business entity or the group, or
Enter a value in one of the two fields.

Error message extract from SAP system. Copyright SAP SE.