There are several reasons a wisteria may not bloom. The most common is the age of the plant. Wisteria can take as much as 8 to 10 years before they begin to bloom, especially if they were grown from seed. In this case, patience is the key.

Other reasons it may not bloom include too much nitrogen encouraging vigorous foliage growth at the expense of flowering; too much shade; and pruning at the wrong time - wisteria should be pruned in late spring, usually after flowering; pruning in late summer and fall will remove flower buds set for the next spring.

Suggestions on how to get it to bloom if all the things mentioned above are not a factor, other than age, is to shock it or stress it which sometimes encourages blooming. Things like keeping it on the lean side with water and nitrogen fertilzer and in some cases root pruning have been suggested, but these methods don't always work, especially if it is an age thing. 

I have heard of some never blooming, even older plants; in that case it is recommended to remove the plant and start over.

So, you may have to be patient and hope it blooms sooner than 10 years.