MATLAB Code for FEA of a simple 6 bar space truss.

Hello everyone! I am trying to practice finite element analysis by solving some textbook problems using finite element analysis instead of the textbook method. I am trying to find the force in each member of the truss for problem 6.37.

The correct textbook solution is:

Member AD: 4.241 KN (Compression)

Member BD: 4.935 KN (Tension)

Member CD: 534 N (Compression)

Member BC: 672.44 N (Tension)

Member AC: 415 N (Compression)

Member AB: 1395 N(Compression)

I have attached my matlab files below. I am able to get the exact correct answer for members AD, BD, and CD, but I am getting a solution of 0 for the remaining members. I set nodal displacements all to zero except for the three nodal degrees of freedom at joint D. I am not sure if maybe I am using incorrect constraints, but any help would be appreciated!