BlueprintImplementableEvent does not work

I want to use a BlueprintImplementableEvent in my UPickableComponent Class that derives from UStaticMeshComponent.

public:
UFUNCTION(BlueprintImplementableEvent)
void OnPick();

I made a Blueprint based on AActor and dropped the UPickableComponent into it. So far so good.
But I am not able to find the OnPick Event in neither the Components details tab or the nor the EventGraph 's context menu. I tested with BlueprintNativeEvent but it also fails.
Are there any common mistakes I coud have made ?

Hi, maybe you wanted to use a delegate that is marked BlueprintAssignable (like e. g. inside the AIPerceptionComponent) ?

Thanks, it works