Buffer management for contiki

Question

I am working with TelosB mote and we are trying to send two different packets (strings) from one mote and trying to receive and print both strings on other mote but on the receiver end it's only receiving one string. I am unable to understand why it's not printing the second string? is this a problem with the buffer or something else?

#include "contiki.h"
#include "net/rime.h"

#include "dev/button-sensor.h"
//#include "powertrace.h"
#include "dev/leds.h"
#include "net/queuebuf.h"
#include <stdio.h>
#include "net/packetbuf.h"
#define QUEUEBUF_NUM 8

/*---------------------------------------------------------------------------*/
PROCESS(example_unicast_process, "Example unicast");
AUTOSTART_PROCESSES(&example_unicast_process);
/*---------------------------------------------------------------------------*/
static void
recv_uc(struct unicast_conn *c, const rimeaddr_t *from)

{
  static struct queuebuf *queuebuf;
  void queuebuf_init(void);
  queuebuf = queuebuf_new_from_packetbuf();
  queuebuf_to_packetbuf(queuebuf);
  printf("unicast message received from %d.%d: '%s'\n",
     from->u8[0], from->u8[1],(char *)queuebuf_dataptr(void static struct queuebuf *b));

  printf("unicast message received from %d.%d: '%s'\n",
     from->u8[0], from->u8[1],(char *)packetbuf_dataptr());


}
static const struct unicast_callbacks unicast_callbacks = {recv_uc};
static struct unicast_conn uc;
/*---------------------------------------------------------------------------*/
PROCESS_THREAD(example_unicast_process, ev, data)
{
  PROCESS_EXITHANDLER(unicast_close(&uc);)

  PROCESS_BEGIN();
  //powertrace_start(CLOCK_SECOND * 2);
  unicast_open(&uc, 146, &unicast_callbacks);






  while(1) {
    static struct etimer et;
    rimeaddr_t addr;

    etimer_set(&et, CLOCK_SECOND*10);

    PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));

    packetbuf_copyfrom("Hello", 6);
    addr.u8[0] = 4;
    addr.u8[1] = 0;

      printf("unicast message sent to %d.%d: '%s'\n",
     addr.u8[0], addr.u8[1],(char *)packetbuf_dataptr());

    etimer_set(&et, CLOCK_SECOND*11);

    PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));

    packetbuf_copyfrom("norway",7);

    addr.u8[0] = 4;
    addr.u8[1] = 0;
   printf("unicast message sent to %d.%d: '%s'\n",
    addr.u8[0], addr.u8[1],(char *)packetbuf_dataptr());

    //leds_toggle(LEDS_BLUE);
    if(!rimeaddr_cmp(&addr, &rimeaddr_node_addr)) {
      unicast_send(&uc, &addr);
    }

  }


  PROCESS_END();
}