Bye and Alf are onto it.
My bet would be that the reasons and drivers for implementing are the cause of the failure.
If the SMS is introduced because the regulator requires it and for no other reason, then it will not be particularly successful.
The CEO, the Chief Pilot, and the head of training have to believe in the value of what is being implemented. If they don't, then the implementation is a waste of money. In addition to believing, they have to be able to communicate those beliefs to the staff. That is what leadership is all about, beliefs. Communicating anything else ( tasks, outcomes, consequences etc) is just management.
Do your highest level managers/ leaders believe in the SMS and it's value?