I am trying to develop a UELMAT for a steady heat transfer analysis. My problem is that my element doesn't work when convection interaction is applied to it. I have tried both to apply this concentrated interaction in the nodes (since superficially it does not work in user-defined elements) and trying to add the FILM subroutine inside the UELMAT subroutine. In all it returns me the nodal temperature as 0 in all the nodes.