Passion Flower

My Passion Flower is two years old and grown from a cutting.  It didn't do anything last year, in fact I thought that it had died.  However this year it has covered a large trellis and wants to get even bigger!  A few weeks ago it was covered in buds, some of which have flowered but most have dropped.  It has about 3 hours of sun in the evening on one side and is in total shade on the other but it doesn't seem to have made much difference as there are flowers and dropped buds on both sides.  It's a shame as we thought it would be covered in flowers.  Any ideas, anyone?