That looks like you should be able to receive. The next thing I would try is a small electrolytic capacitor on your 3v3 source. Say something along the lines of 10uF - 47uF; between vcc and gnd. I know some mega2560s require this because the 3v3 regulator stinks. Especially if using a LR radio. Mine requires this. Without it, TX is unreliable on the SR units and almost impossible with a LR radio. For paranoia's sake, you might also consider a 10pF decoupling capacitor.