Thank you for your answer. I tried all you said but I am still getting the same error.nMy model as shown in the picture. I use two permanent magnets and iron core above the magnets. Steel plate in the band as you see in the picture. No holes, no hollow geometry as you see in the picture. Also vacuum object enclose everything. There is only one object in the band. Actually I tried multiple objects and one object in the band according to you said. None of all did not work.nn