The conjunction of Sun and Mercury forms Budh Aditya Yoga. This is a great yoga to have in a horoscope which bestows intelligence, good health, analytical, planner and strategist mind. The person has strong communication skills and is a negotiator. Below I explain why and how despite Mercury and Sun being together in a horoscope, this yoga will not be there.
Conditions under which Budh Aditya Yoga will not be there:
Those who follow Vedic astrology should remember that not every time Sun and Mercury are conjoined it will form the Auspicious Budh Aditya Yoga. One very important thing is that Mercury never moves further than 28 degrees further to the Sun. Therefore in any horoscope you will always find Mercury and Sun are conjoined. Does it mean that every Horoscope has a Budh Aditya Yoga by default. This is not so and the reason is that Budh or Mercury gets combust when less than 13 degrees with the Sun. Therefore whenever Mercury is combust it loses its own power. Therefore this yoga will not be formed when Mercury is less than 13 degrees from the Sun which makes it combust.
Another reason when this yoga is not formed is when in a horoscope Sun or Mercury are debilitated , that means Sun in Libra and Mercury in Pisces. This Yoga is also not formed when Mercury or Sun is lord of the 6th, 8th and the 12th house, which are the trik bhavas or the malefic house.
Honestly speaking many people do not go into details when they see this yoga and that is why the native does not get the desired results.
You may watch a the below Video where Astrologer Navneet Khanna, speaks more on the Budh Aditya Yoga and explains what are the reasons that this yoga may not work for you.