How do I get "ears" or the folding back of the layer on top of the bread?

How do I get "ears" or the folding back of the layer on top of the bread?

I have been baking the standard whole wheat sandwich loaf of bread for over 10 years and find that the crust and crumb are fine. However, after I slice the top of the loaf prior to putting it in the oven, I can not get it to unfold or pull back the way I prefer.

I slice with a razor blade; I bake the loaves at  425 degrees for an hour. But there are no ears for folding back on top of the loaf.

What am I doing wrong?