ATtiny84 nRF24L01 TMRh20 (once again)

Hi Folks,

I am new to this forum, new to arduino and new to nRF24L01. Ofcourse I am, otherwise I would not ask such dumb questions.
I try to set up an ATtiny84 with an nRF24L01+ module to send data (temperature and humidity, what else? :wink: ) to an raspberry pi with another nRF24L01+ module.
As the TMRh20-Lib offers examples for Arduino, ATtiny84/85 and RPI i choose this lib. First of all i tried to get a connection between two RPIs with nRF24L01+ modules. After wiring everything up the connection was stable and everything was running like expected.
Then i tried to set up a ATtiny84 with the nRF-Module. I wired it up like explained in the sketch rf24ping85.ino and configured CE_PIN and CSN_PIN and set the addresses like they are set in the RPI-Example "transfer.cpp"

    ATtiny24/44/84 Pin map with CE_PIN 8 and CSN_PIN 7
	Schematic provided and successfully tested by Carmine Pastore (https://github.com/Carminepz)
                                  +-\/-+
    nRF24L01  VCC, pin2 --- VCC  1|o   |14 GND --- nRF24L01  GND, pin1
                            PB0  2|    |13 AREF
                            PB1  3|    |12 PA1
                            PB3  4|    |11 PA2 --- nRF24L01   CE, pin3
                            PB2  5|    |10 PA3 --- nRF24L01  CSN, pin4
                            PA7  6|    |9  PA4 --- nRF24L01  SCK, pin5
    nRF24L01 MOSI, pin7 --- PA6  7|    |8  PA5 --- nRF24L01 MISO, pin6
                                  +----+
*/

// CE and CSN are configurable, specified values for ATtiny85 as connected above
#define CE_PIN 11
#define CSN_PIN 12
//#define CSN_PIN 3 // uncomment for ATtiny85 3 pins solution

#include "RF24.h"

RF24 radio(CE_PIN, CSN_PIN);
const uint64_t addresses[2] = { 0xABCDABCD71LL, 0x544d52687CLL };
//byte addresses[][6] = {
//  "1Node","2Node"};

The sketch compiled without any errors and is running on the ATtiny84 as i can see in a serial terminal with a little Serial.println("Ping....") after calling the radio.write(...) function.

On the RPI in the transfer-example I removed some init-functions to the the RF24-init equal on RPI and ATtiny84.
This is what it looks like on the RPI:

  printf("RF24/examples/Transfer/\n");

  radio.begin();                           // Setup and configure rf radio
//  radio.setChannel(1);
//  radio.setPALevel(RF24_PA_MAX);
//  radio.setDataRate(RF24_1MBPS);
  radio.setAutoAck(1);                     // Ensure autoACK is enabled
  radio.setRetries(2,15);                  // Optionally, increase the delay be$
//  radio.setCRCLength(RF24_CRC_8);
  radio.printDetails();

These are all the changes I made in the examples. Up to now I was not able to receive anything from the ATtiny84 at the RPI. I ran out of known options to check for.
Maybe some of you can point me to possible solutions?

Thanking you in anticipation
Jan