I think that you should put just this in groups: "admin": {title : "Administrative Boundary", exclusive : true }, "background" : { title : "Base Layers", exclusive : true

And in your background layer, try to put visibility:true instead of inBaseLayer:true

I put it in that way and it works..Good luck!

I think that you should put just this in groups: "admin":

{title : "Administrative Boundary",
                    exclusive : true
                },
                "background" : {
                    title : "Base Layers",
                    exclusive : true

And in your background layer, try to put visibility:true instead of inBaseLayer:true

I put it in that way and it works.