Free body force function

We like to obtain the forces at a lug of a pressure vessel.However we do not restrain the vessel at the lug but still need toobtain forces at the lug due to internal design pressure etc. Thefree body function seems to be the way to go but it gives us aforce of zero.

Please explain how this function works and if there is other way toobtain the forces?

SolidworksSimulation