it's meant to be down to the pruning. I have followed the instructions in the books but mine has never flowered either. even though it came from a flowering parent.
Sorry I'm not much help.

I have 3 and none of them ever flowered until last year. I did a lot of research online and stumbled across Alan Titchmash on you tube pruning his wisteria, I did that every year for 3 years and last year I got lovely flowers on one of them. This year I have flower buds, hundreds of the m on 2 of my wisterias and only a few buds on the third one, the third one is in a shady spot in the garden so I am putting it down to that, but I am encouraged that it has a few buds. I was also advised to feed them Tomorite throughout the summer season which I did every week or so and I even fed them during the winter as it was suggested by another gardner online that this was the best time to feed as the flowers come first and then the leaves. I think you have to get the pruning just right, prune the wispy new growth in August and in January prune each branch to 3 buds, prune on a downward angle so raindrops dont affect any buds. Good luck

to marion1 thanks for the advice I'll try it, I've got nothing to lose

And everything to gain, Aidret.
My partner fell in love with wisteria so I bought one for him to grow on the south facing wall of his house. It flowered beautifully for a year or so and then died back.
The replacement flowered well too, but pruning the well established plant has challenged his head for heights. I shall be very surprised if it flowers at all this year. :-(