Binding for event is incorrect - no activation possible

What causes this issue?

Binding for this event is incorrect, either because of incorrect
assignments or because binding is completely missing for events with
obligatory binding.

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?

Use the "Check" function to check each binding assignment. If the event
is subject to obligatory binding, arrange for binding to take place as
required.

Error message extract from SAP system. Copyright SAP SE.