My point was that you can get the black box to do things that make the model cr8p. Unless you understand how the solver operates and works you wont even know what your doing is incorrect/badly modelled.
iges files tend to be made up of geometric entities (surfaces,points,curves) and not dumb solids. So when you import it you have no solid if you wish to mesh with solid elements. You would first need to create a solid model from the independent separate geometry. If your iges file comes in as solid then you need to be able to model in 3d elements, and by the sounds of your post, if you cant mesh in solids anyways then your stuck unless you change to another option. I would recommend the nastran/patran option as its stable, well trodden and easy to use.