There you go!
In my case, I had to write some outputs Low so that the interrupt could be created by a key press, then write them back high again before the keypad library would work. Glad to see you found a way to get your interrupt created as well.
I have a 8MHz promini, and ended up doubling the serial.begin(speed) to have it talk correctly via serial port for debugging, and doubling the speed set for Virtualwire RF to have that work as well. Am guessing the chip is set for 16MHz operation (maybe something I did during downloading without realizing it?) but with 8MHz xtal, external comms need to be set to 2X so operate at the correct speed.