Why won't my Wisteria grow?

I bought it last June as part of a scheme for a new garden, and planted it up on a trellis against a sunny wall (unwinding it from it's three bamboo canes it was wrapped around when purchased from the nursery and re-winding it around the trellis using it's natural 'curls'). I had just dug the bed in which I planted it, the soil consisting of a mix of manure, pea shingle, peat-free compost and topsoil. It has been well fed and watered, but has never really developed to more than a twiggy stem with the odd bit of leafy growth. It is no taller or thicker than when I bought it and it appears to have had some kind of setback already after appearing to have a good start to May - the leaves and new growth that appeared have all shrivelled and wilted. I thought it may have gotten dried out on one of the warmer days, yet all info online suggests it needs, and thrives in, decent sunlight. It is the only plant in our garden that has not taken off - what is going wrong...!?!