Your original code would have worked if you had written elapsed instead of elapse. The suggestion p3lim came with will also work, but in the zip above you have defined your OnUpdate handler twice.
The first suggestion humfras came with isn't correct, as arg1 doesn't exist anymore. This is also your current second definition of OnUpdate, so it overrides the correct one.
Also, I would recommend you to tell people how they can recreate the error, especially when you hand them a couple of thousand lines of Lua and XML.
