With the democratization of informatics technologies, there is a new demand for more advanced Virtual Learning Environments (VLE) and also fancy training devices that integrate technologies like Augmented Reality (AR) or Virtual Reality (VR). The fact that these solutions are now affordable makes the learning managers dream about having realistic simulations for training. When delivered, sometimes customers are not satisfied because the software is often complex, not user-friendly enough, or not compatible with the computer fleet of the company. Consequently, professionals show a preference for the old training solution. In this chapter, the crash case of a French university commissioning a simulator on VR for training operators on the production of anti-cancer drugs will be presented. The authors will highlight the reasons that made this training not adapted to the field in which the training takes place, then, explain which guidelines an effective instructional designer should take into consideration while developing the training solution.