The only way to get business commitment is to deliver a working system. So the business should only be involved in the user acceptance testing, the last testing phase before the production acceptance and implementation. When the people in the organization see that the product actually works, then they will become enthusiastic. However, to get business commitment we need more.
As we said the business knows the processes. So the business should be involved in setting up the requirements. That way their knowledge is used in a constructive way plus they are involved. It is important to get the knowledge of the current processes clear to be able to improve them.
In projects in which realization and testing is done in an isolated team, that has little contact with the business, the business complains that “we know they are doing something but we don’t know what”. That is not a desirable situation either. Therefore it is a good idea for the project manager to give a presentation to the business a couple of times during the project of what has been done and what is to be expected. The project team would stay in contact with the business and could use the feedback from the business to adjust the course of the project in the right direction.