Arduino Uno/Nano and NRF24L01 2.4GHz Module Problem

Hey guys, I have a small problem that I don't understand.

I have a arduino nano with nothing but the NRF24L01 modul connected as a sender, it uses the following code:

#include <SPI.h>
#include "nRF24L01.h"
#include "RF24.h"
#include "printf.h"

int msg[1];
RF24 radio(9,10);
const uint64_t pipe = 0xE8E8F0F0E1LL;

void setup(void){
  Serial.begin(9600);
  printf_begin();
  radio.begin();
//  radio.setDataRate(RF24_250KBPS);
//  radio.setPALevel(RF24_PA_MAX);
//  radio.setChannel(70);
//  radio.setRetries(15,15);
//  radio.setCRCLength(RF24_CRC_16);
  radio.openWritingPipe(pipe);
  radio.printDetails();
  Serial.println();
  Serial.println("Ready.");
  delay(50);
}
 
void loop(void){
  for (int x=0;x<255;x++){
    msg[0] = x;
    Serial.println(msg[0]);
    radio.write(msg, 1);
    delay(1500);
  }
}

(I tried it with and without commenting these five currently commented lines)

And also an arduino uno with the same module and an RFID-Card reader on SPI.
The arduino uno currently has the following code loaded:

#include <nRF24L01.h>
#include <RF24.h>
#include <RF24_config.h>
#include <SPI.h>
#include "printf.h"

int msg[1];
RF24 radio(7,4);
const uint64_t pipe = 0xE8E8F0F0E1LL;
 
void setup(void){
  Serial.begin(9600);
  printf_begin();
  radio.begin();
//  radio.setDataRate(RF24_250KBPS);
//  radio.setPALevel(RF24_PA_MAX);
//  radio.setChannel(70);
//  radio.setRetries(15,15);
//  radio.setCRCLength(RF24_CRC_16);
  radio.openReadingPipe(1,pipe);
  radio.startListening();
  radio.printDetails();
  Serial.println();
  Serial.println("Ready.");
}
 
void loop(void){
  if (radio.available()){
    bool done = false;  
      
    while (!done){
      done = radio.read(msg, 2);
      Serial.println(msg[0]);
     }
    }
}

Got the code from here, just modified it a bit.
The Nano is definitely sending, I've used a CC308+ to test it.
The wiring is definitely okay too, when I try a complete serial chat using the exact same hardware setup, it works. The RFID-Card reader is working too, so I'm sure I didn't mess up the SPI wiring.

Some very very very rare times the uno received the "0" the nano sends at first, but that happens only once a day in lots of tries. No changes in the hardware or wires at all.
The chat works all the times. I also tried the RF24 send/receive example: Sometimes it works, most times that one doesn't work too.

I have no clue what to check and what I could look for. Thanks in advance for any help!

The result of "radio.printDetails();" (with these five lines commented out):

Receiver:

STATUS           = 0x0e RX_DR=0 TX_DS=0 MAX_RT=0 RX_P_NO=7 TX_FULL=0
RX_ADDR_P0-1     = 0x00d41e1141 0xe8e8f0f0e1
RX_ADDR_P2-5     = 0xc3 0xc4 0xc5 0xc6
TX_ADDR          = 0xe7e7e7e7e7
RX_PW_P0-6       = 0x00 0x20 0x00 0x00 0x00 0x00
EN_AA            = 0x3f
EN_RXADDR        = 0x03
RF_CH            = 0x4c
RF_SETUP         = 0x07
CONFIG           = 0x0f
DYNPD/FEATURE    = 0x00 0x00
Data Rate        = 1MBPS
Model            = nRF24L01+
CRC Length       = 16 bits
PA Power         = PA_HIGH

Sender:

STATUS           = 0x0e RX_DR=0 TX_DS=0 MAX_RT=0 RX_P_NO=7 TX_FULL=0
RX_ADDR_P0-1     = 0xe8e8f0f0e1 0xc2c2c2c2c2
RX_ADDR_P2-5     = 0xc3 0xc4 0xc5 0xc6
TX_ADDR          = 0xe8e8f0f0e1
RX_PW_P0-6       = 0x20 0x00 0x00 0x00 0x00 0x00
EN_AA            = 0x3f
EN_RXADDR        = 0x03
RF_CH            = 0x4c
RF_SETUP         = 0x07
CONFIG           = 0x0c
DYNPD/FEATURE    = 0x00 0x00
Data Rate        = 1MBPS
Model            = nRF24L01+
CRC Length       = 16 bits
PA Power         = PA_HIGH

I notice you have a long delay(). That may cause a problem if you are using the older ManiacBug version of the RF24 library.

I suggest you use the TMRh20 version of the RF24 library - its API is nearly identical.

Unfortunately TMRh20 decided to use the same name for his version which can be confusing. For my own use I have renamed his library.

...R

Robin2:
I notice you have a long delay(). That may cause a problem if you are using the older ManiacBug version of the RF24 library.

I suggest you use the TMRh20 version of the RF24 library - its API is nearly identical.

Unfortunately TMRh20 decided to use the same name for his version which can be confusing. For my own use I have renamed his library.

...R

Thank you VERY much!
I was indeed using the ManiacBug version. Tried the one you suggested and it worked!