Although we endeavour to do everything necessary to heal ourselves and others who are sick or injured, we cannot forget certain laws of Karma. It is possible that due to some karmic destiny, it needs to be either balanced by suffering or some lessons need to be learnt so that you can heal others. Healing is not a hit and miss affair, even though to human perception it may seem so.
Most healers will find that not everyone benefits, even from the best doctors for unknown reasons. A person may not believe in Yoga, Meditation, Ayurveda, Acupressure or Homeopathy Medicine but it is also possible that he could be healed faster than a person who does believe in these therapies. It is important for the patient to have trust in Doctor or Healer. The receptivity of the person to be healed is equally important.