Bread-Bakers v097.n037.15

This will probably sound incredibly naive, but my yeast breads always turn out
dense instead of light and fluffy, and I want to know why!!!! :-)  Help!
(I use the Kitchen Aid dough hook for mixing and kneading.)

For some context, I recently made a loaf of Potato Bread.  The recipe was
given to me by my aunt.  I've had her potato bread and it has a light texture.
My loaf was dense. :-(  

Thanks for any insight-
jenni