Non volatile memory problems

I'm used rcm5600w with DC 10.56. I try to store data in nonvolatile memory with the following code, the problem arise when I tried unplugging the power supply for a few minutes and turn on the power supply to read the data I stored, I lost the data. Is there any wrong with this program? Thanks.

#use "rcm56xxw.lib"

#define dataADDR 0x1B28BUL // physical address of nonvolatile memory
#define dataLength 12

char *const data = "this is data";
char *temp;

void main(){

    brdInit();

   // close this line and remove power supply 
   //  for testing nonvolatile memory
   // write data to nonvolatile memory
   //root2xmem(dataADDR, &data, dataLength);

   // read data from nonvolatile memory and store to temp array
   xmem2root(&temp, dataADDR, dataLength);

   if(memcmp(&temp, &data, dataLength)==0){
       printf("data is equal with temp\n");
   }
   else {
       printf("data isn't equal with temp\n");
       printf("%s\n", temp);
   }
}