Problems with theme

I just wanted to install my new theme to my live site; I have developed my theme on a local machine and everything works fine. However, when I try it on my live site something goes wrong. Whenever I press update on a page I get a blank screen. When I deactivate the theme suddenly everything works fine again. So I’m pretty sure it’s the theme. But how can it work on one installation and not on the other? It’s the same vrsion of wordpress. (I updated the live site from 2.7 tot 3.2 with the updater but everything seems fine)