If you read and, closely, follow Robin2's simple rf24 tutorial you should be able to get them working. That tutorial sure helped me. The code in the examples is, I think, simpler than the RadioHead examples and has been proven to work many many times. If it does not work for you, there is likely a hardware problem.
Run the CheckConnection.ino (look in reply #30 in the tutorial) to verify the physical wiring between the radio module and its processor (Arduino).
Some other tips:
If using the high powered radios make sure to separate them by a few meters. They may not work too close together. Try the lower power settings.
Reset the radios by cycling power to them after uploading new code. I have found that to help. They do not reset with the Arduino.
Have a look at the common problems page.