Too much water promotes foliage growth over bud production.

I always water mine extensively through June, at which point they've pretty much covered the privacy fence they are planted under. Then I cut way back on the watering and they'll start flowering like crazy.

I water mine well in the beginning as well, they do like poor soil and mostly neglect. I planted five packs in a bed last year, they all sprouted and there was a bunch of them, when they started to flower I didn't water as much but the soil stayed fairly moist due to the vines covering the ground and shading it, mine did fine. It's not too late to try again.