compiler doesn't have override & overload of indexed properties

I get a compiler error on the second property (BCE0060: Boo.Lang.Compiler.CompilerError: 'Second.get_Demo()': no suitable method found to override.)

class First:
virtual Demo(i as string):
get:
return null

class Second(First):
override Demo(i as string):
get:
return null

Demo:
get:
return null