An ExtensionPoint can only be referenced by an << extend >> UseCaseDependency.
An ExtensionPoint is a feature of a UseCase that identifies a point where the behavior of a UseCase can be augmented with elements of another (extending) UseCase. Therefore, only << extend >> UseCaseDependencies can reference an ExtensionPoint.
Replace the incriminated << include >> UseCaseDependency with an << extend >> UseCaseDependency.