The very first time they don’t respond, stop and find out why. It is possible that they may be intentionally blocking the process, for some unknown reason. Yet, in my experience, it is more likely that they did not fully understand what was expected of them.
Quite often it seems this happens if you skip from permissive to direct too early in the process – and they don’t know how to do what you are asking of them.
There is no reason that you cannot repeat the first suggestion – that they take themselves back – more than once. This enables them to feel at ease with the process, ensures that they have learned what is required of them and increases the effect of the fractionation.