I might be going blind, but the only assignment to a bool that Ican see is:
Not counting the assignment of false obviously.
This implies that radio.read() is returning void and not a bool value. You need to check in the headerfile for the radio class, for the return type for read().
Either put getData() above any other function which calls it, like loop(), or, just add:
unsigned long getData();
After the various includes. In C++ you must declare any function before it is called. The Arduino system hides this from you. As demonstrated here: Tutorial for creating multi cpp file arduino project - #38 by normandunbar
Cheers,
Norm.