I am trying to do a nonlinear transient heat transfer analysis. I referred to example analysis (https://2021.help.altair.com/2021/hwsolvers/os/topics/solvers/os/manifold_nonlinear_transient_heat_transfer_os_example_r.htm) and created my model accordingly. As you can see from pics, the subcase card in my model is identical to the example. Despite this, the solver is unable to run my model due to Error 1461. The Optistruct manual also instructs to use DLOAD in subcase to reference to TLOAD load collector...