Mac OS 10.7.3 not launching application from custom url scheme

Question

I have developed a software that launches from a custom url scheme (something like "myapp://123"). It works on two of my test Mac machines (running 10.7.3 and 10.8 respectively) but somehow it doesn't work on another machine running 10.7.3

Are there any system settings that disable custom url scheme, or anyway I could troubleshoot this problem?

Thanks!