Removing material works but won't remove


Hi.
I am using Creo Panametric 8.0. I am new to this programme, but for whatever reason I can't figure out why my removing material when extruding doesn't work. I have looked at other forums but nothing seemed to work. This includes changing the type from solid to surface, as well as making the extrusion into different shapes: some shapes seem to work, some do not.
I have made an extrusion out of ellipse and line tool and want to cut that extrusion out of my current cuboid.
I have the "remove material" selected and it goes through the cuboid but it doesn't remove any material.
Thanks

