Button not working on iPhone

I'm developing a new responsive version of my website at test dot [example] dot com

On the home page is a search box, and for some reason the search button is not working on my iPhone. It works fine on all other browsers, on several responsive design testers, and works fine using the iPhone user agent function of the Safari browser on my computer, but it just doesn't work on the actual iPhone. Any ideas?

[edited by: phranque at 11:08 pm (utc) on Oct 1, 2013]
[edit reason] exemplified domain [/edit]