Question
why do the buds fall off my orchid plant and not flower

Answer
Leslie, there are many factors that influence bud drop.  You might help me to help you by giving me some further information.  Is this a recently purchased plant or has it flowered for you before?  How long have you had it?  Has it been exposed to any cold or dry conditions?  Where do you grow it and what is it potted in?  Does the flower spike remain green after the bud drop?  How many leaves does the plant have?   I'll await any additional information you can provide to help me diagnose the cause of bud drop.