Hi!
It seems to me that the page you are calling with the method numChildren() from your template may not exist. But, I guess, I cannot point out where exactly is the problem, until I see the code My procedure of moving to the live server is a bit different. On the live server I install a clean PW, then I move my templates there and create a backup of sql using ProcessDatabaseBackups to import it back on my live server. Yeah, more steps to do, but works for me
Greeting from Lithuania.