Hy,
Your main problem is the def definition.
def.DOF is not equal to model.DOF but just equal to model.Stack{1,3}.DOF
The software compute the solution
>> def.def
ans =
(1,1) -1.3808e-002
(2,1) 3.3156e-002
(3,1) 3.9453e-002
(4,1) 6.9714e-003
(5,1)...