Reactive systems are complex systems which behavior can be adequately modeled using the statechart formalism. The UML standard enriches this formalism with object-oriented concepts. However, manual transformation of these expressive models to object-oriented languages is an error-prone process. Model-Driven Engineering approach advocates for an automatic process to translate models into high-level programing languages. This work deals with the conversion of UML State Machines models into Ada 2005 code and the challenges that arise in this process.