No-one said transforming an organisation was easy. Having been in charge of many large scale global transformations, this is a good article which explores common blind spots and how to overcome them to increase your odds of success.

In my experience, the critical factors are why, what and how. The 'why' needs to be created and consistently shown and talked about by the executives. This gives emotional reasoning and logical rational behind the 'whats' of the programme. What is going to change and what is staying the same? People will need to know both and how they fit into the 'why'. 

Finally, people need to know 'how' this affects them, and how their day-to-day job will need to alter. Communicating and engaging with this population in a way which helps them to understand and buy-in is critical to any significant organisational change. This comes down to effective leadership.