Problem with CFNetRegister

Question

I'm trying to work with CFNetServices by trying to start up and publish a service asynchronously.

I'm trying to use the example code from here: http://developer.apple.com/mac/library/documentation/Networking/Conceptual/NSNetServiceProgGuide/Articles/CFNetServices.html#//apple_ref/doc/uid/30001276-SW3, but CFNetRegisterWithOptions always fails. (CFNetRegister is deprecated now). When I print out the error struct, it looks like this:

(gdb) p error
$1 = {
  domain = 10, 
  error = -72004
}

Which doesn't seem correct to me. Does anyone know what might be wrong? Thanks!