Problem in improving optimization of engine pylon model

Hi I am doing some topology optimisation on a 3D engine pylon and I have a problem in trying to to improve the optimisation of the engine pylon model. However, I only have the altair optistruct available to use.  The boundary and load conditions are based on the image below. The fixation represents the boundary conditions and the circle shaped hanging position is weight of GE90 engine and the triangle shaped hanging position is the thrust of GE90 engine. The optimisation is meant to look like the second picture but my optimisation looks like the one below. So I am wondering what can I do to improve the optimisation of the engine pylon model as I have changed the volume constraint from 0.3 to 0.2 and there is no difference. Does it mean that I applied the boundary and load conditions incorrectly? I do not know what to do to improve the optimisation of the engine pylon model so the third image looks similar to the second image. 

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