Some people simply cannot be directed, no matter what we tell them. This makes us feel powerless, and so we fall back to the argument ‘Because I say so!’.
When someone doesn’t take action (or they choose not to do something) they usually don’t see what’s in it for them. This isn’t necessarily a business interest; it could very well have to do with their family or soccer club.
I believe that anyone in a leading position should carefully explain the reasoning behind their commands.
If you do so and the other person still refuses to carry out your request, he probably just doesn’t want to.