Yes, elections are valid only if the votes are counted correctly. There's lots of concern over the touch screen machines and whether voters can verify the way they voted. See this post over at Project on Government Oversight.
But I'm a bit bemused--I voted for years using the old mechanical lever machines and wasn't able to verify my vote once. For all I know, it was all fake machinery and the real results were arrived at by the election workers. For some reason, the clanking of machinery seems more convincing and more reliable than the transfer of elections. I wonder why?