Master detail doesn't work.

I was following master detail tutorial here, there was no classes provided to completely finish it so i made up my own and now I can't get it to work, can someone look into where I went wrong?

I used ObservableCollection and did my Property notifications in my classes, i think the problem is in xaml.

xaml: http://pastebin.com/H4nYhtyU

viewModelBase.cs: http://pastebin.com/3YFcBrg1

customerListViewModel.cs: http://pastebin.com/E1g3Lys4

customerViewModel.cs: http://pastebin.com/XzGeji3E

serviceViewModel.cs: http://pastebin.com/w6hVqrsv