Subtract tool not working?

I have selected two bodies (the targets) and two additional bodies (the tools) but I do not get the “Done” button, so can’t proceed. Help?

Hello RTFM,

Try “fiddling” with the items you are trying to subtract. Move and or making them slightly larger. This usually works for me.
It won’t subtract because something is not exactly right.

It looks like the parts you want to subtract have already been subtracted. In other words, the two rods don’t intersect with the large part because the holes are already there. Hide the rods and see if I’m right.