I planted 2 crape myrtle bushes at the edge of my Eastern Kentucky country driveway 12 years ago, when I first bought my home. They were (marginally) in bloom when I bought them, but they haven't bloomed since, though they've grown very large, and seem healthy. This year, one branch has a cluster of flowers on it - no more. My neighbors all have large, heavily blooming trees. They're in full sun, I've fertilized, pruned, not pruned - tried everything I could think of. Any help out there? I'm missing something...!