FYI for those who are newbs trying to use the RFM69 library like me... apparently when you send the packet, you need to reference the array using pointers. My problem was that I was missing an & before my variable 'message'.
It should have looked like this:
radio.sendWithRetry(TONODEID, &message, 1);
when sending a single byte.
When sending an array of bytes, if my variable was message[5] then I could use it without the ampersand.
radio.sendWithRetry(TONODEID, message, 1);