If you read and, closely, follow Robin2's simple rf24 tutorial you should be able to get them working. That tutorial sure helped me. Run the CheckConnection.ino (look in reply #30) to verify wiring between the radio module and its processor (Arduino).
Make sure the rf24 power supply can provide enough current. I use homemade adapters like these. They are powered by 5V and have a 3.3V regulator on the board.
If using the high powered radios make sure to separate them by a few meters. They may not work too close together.
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.
Switch to 1MB data rate to catch the not so cloned clones.
thanks for your answer, but im pretty sure the connections are all fine, since i get perfect communication with the nrfLite library.
I also tested the checkConnections sketch and it also looked alright.
I can't fully explain it, but my observation has been that acknowledgements can be disproportionately affected by inadequate power. It could be something to do with number of preceding retries and the necessary recovery period afterwards.
Anyway, if you are using the 3.3volt output of a normal Nano, then that is likely to be the explanation for erratic behaviour irrespective of the add-on 10uF capacitor. The power is simply insufficient. This is especially so if you are using the modules described as nRF24L01+PA+LNA.
sadly even after connecting the nrf modules to my bench power supply at 3.3V and trying various different speed and frequencies i still couldn't get a stable connection. So i will be staying with the nrflite library because there the connection works, even so i would have liked to use the more powerful rf24 library.
Well, it appears to work sometimes so it is not as clear cut as that but it would be good to have a picture / supplier link of those modules. The modules sold as nRF24L01+PA+LNA are more prone to problems (a) because these have higher power requirements and (b) because these have 2 chips which could be fakes/clones, increasing the scope for problems.