Bread-Bakers v108.n016.1

Jim, my guess is you need a higher protein flour. Many all-purpose 
flours are around 9% protein and you need more like 13%. Try mixing 
King Arthur Unbleached Bread Flour and their Whole Wheat flour 2 to 1 
and see how that works for you. The higher protein flours are more 
expensive but it's worth it!