Thanks for the effort Larry but I get the same result with one or three or fifteen buttons (in order to fully test a radio button you must have a least two present), do you have "Highlight" turned off in your Acrobat? If not I would like to know how you did it. Did you use a button from the "Button Library"?, are you using CC or CC 2014? Maybe you can share you InDesign File .....
I am pretty sure there is a way to accomplish this I saw a video online where someone was able to do so, I have reached out to the individual but have not heard back from him.
Thanks
Mark