The method to get Coordinator IEEE address?

Hi All:

    I wrote a program to get the End device information, such as short address, IEEE address etc. But when I tried to get the Coordinator address, I got nothing, just messy code. I don't know why.

The structure I defined:

typedef struct RFTXBUF
{
  uint8 type[3];
  uint8 myNWK[4];
  uint8 myMAC[16];
  uint8 pNWK[4];
  uint8 pMAC[16];
}RFTX;

In the End device SendTheMessage() function:

if (DistanceApp_NwState == DEV_END_DEVICE)
  {
    osal_memcpy(rftx.type,"END",3);
  }
 
  if (DistanceApp_NwState == DEV_ROUTER)
  {
    osal_memcpy(rftx.type,"ROU",3);
  }
 
  nwk = NLME_GetShortAddr();
  To_string(rftx.myNWK,(uint8 *)&nwk,2);
 
  To_string(rftx.myMAC,NLME_GetExtAddr(),8);  //The IEEE address is right
 
  nwk = NLME_GetCoordShortAddr();
  To_string(rftx.pNWK,(uint8 *)&nwk,2);  
 
  NLME_GetCoordExtAddr(buf);   //there is only messy code in the buf;
  To_string(rftx.myMAC,buf,8);