Old joystick

Hi all

I bought a copy of X-plane the other day and would like to use my old Gravis joystick with it as it was quite a good stick in it's day. I have bought the 15 pin the usb convertor and system profiler sees it as a 4 button 4 axit stick but config tools in x-plane doesn't recognise there being a joystick there. Have I missed something in setting up an old joystick on mac? has anyone else tried this?

Ta

James