Remember each and every graha have vedhit sthan.
If grah is vedhit it will not be able to give effects!!
For example:if surya (in black horoscope) is passing through 3,6,10 or 11 house.which are good reasultive house of it.but at the same time exept shanï any other planets are in 9,12,4 or 5 th house then surya will not be able to give good reasult i.e. no shubha fala!!!