While I don’t use the binding anymore, I still have my old sitemap for reference. I was using the following Switch:
Switch item=Areas_Main_Mode label="" mappings=["Off"=Off,"Day"=Day,"Night"=Night, "Away"=Away,"Vacation"=Vaca]
my item looked like:
String Areas_Main_Mode "Mode: [%s]" (Areas_Main) {omnilink="area_status_mode:1"}
I would also suggest looking at the logs and seeing what String is being passed to the item when he clicks on a button.