RFM98 (in FSK Modus) - FIFO Problem (sendet nichts)

void rfm98_init(void)

{

    //SPI master init

  DDRB = (1<<SDO) | (1<<SCK) | (1<<CS) | (1<<RESET); // Set MOSI and SCK output

  SPCR = (1<<SPE) | (1<<MSTR) | (1<<SPR0);

  SPSR|=(1<<SPI2X);

    //Reset rfm

    PORTB &= ~ (1<<RESET);  

    _delay_ms(1);

    PORTB |= (1<<RESET);

    _delay_ms(5);

    //set sleep mode for setting

    rfm98_write(0x01, 0x00);

    // Wait for setup mode

    _delay_ms(100);

    if(rfm98_read(0x01) != 0x00) {

      usart_write_str("!sleep: ");

      usart_write_char(rfm98_read(0x01));

      usart_write_char(0x10);

    }

    //RegOpMode (0x01) set mode FSTx

    rfm98_write(0x01, 0x40); // FSK, high freq mod, FSTx mode

    // Wait for setup mode

    _delay_ms(100);

    if(rfm98_read(0x01) != 0x40) {

      usart_write_str("!FSTx: ");

      usart_write_char(rfm98_read(0x01));

      usart_write_char(0x50);

    }

    //set BitRate: RegBitrateMsb and RegBitrateLsb

    rfm98_write(0x02, 0x01);

    rfm98_write(0x03, 0x16);

    //RegSyncConfig 

    rfm98_write(0x27,0x18); 

    //RegFrfLsb | set frequence | Frf = Fstep x Frf(23;0) | Fstep = Fxosc/2^19

    uint32_t frf = (434.5 * 1000000.0) / FSTEP;

    rfm98_write(0x06, (frf >> 16) & 0xff);

    rfm98_write(0x07, (frf >> 8) & 0xff);

    rfm98_write(0x08, frf & 0xff);

}

void rfm98_sendpacket(unsigned char *data, unsigned char size)

{  

  unsigned char i;

  if (size>64) size=64;

  // clear RegFifo

  rfm98_write(0x00, 0x00);    // clear Fifo

    //RegPacketConf1

    rfm98_write(0x30, 0x00);

    //RegPacketConf2

    rfm98_write(0x31, 0x02);

    //RegPayloadLength

    rfm98_write(0x32, size);

    //RegFifoThresh (TxStartCondition)

    rfm98_write(0x35, 0x01);

    if(rfm98_read(0x35) != 0x01) {

      usart_write_str("!TxStCond: ");

      usart_write_char(rfm98_read(0x35));

      usart_write_char(0x01);

    }

    //till here working!

    //RegOpMode (0x01) set mode Tx 

    rfm98_write(0x01, 0x60); 

    // Wait for setup mode

    _delay_ms(100);

    if(rfm98_read(0x01) != 0x60) {

      usart_write_str("!Tx: ");

      usart_write_char(rfm98_read(0x01));

      usart_write_char(0x60);

    } 

  for (i = 0; i<size; i++)

  {   

    rfm98_write(0x00, *data++); //fifo

        //usart_write_char(rfm98_read(0x00));

  }

    usart_write_char(rfm98_read(0x3e));

    usart_write_char(rfm98_read(0x3f));

}