What does Kant mean when he says that an action has moral worth only if it is done ‘from the motive of duty’? Is he right?

A person’s actions are right or wrong, a person is morally worthy or lacks moral worth (i.e., is morally base).  A person’s actions determine her moral worth, but there is more to this than merely seeing if the actions are right or wrong.

All the things we do can be divided into those things which are voluntary actions, and those that are mere behaviour (e.g., knee jerk reflexes).  Of course there is no moral worth based on mere behaviours.  All voluntary actions can be divided into those that are contrary to duty and those which are not contrary to duty.  Kant claims that this distinction is based on the categorical imperative.  Clearly, no moral worth is attained by doing actions that are contrary to duty.  All those action that are not contrary to duty can be divided again into those action which are required by duty and those actions which are not required by duty.  Actions tha…(short extract)