No activity type groups exist for the entry

What causes this issue?

You have called up the possible entries for activity groups. However, no
activity groups have been created in this particular controlling area.

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?

Define the activity groups you require for planning, using the relevant
functions in the 'Master data' menu.

Error message extract from SAP system. Copyright SAP SE.