fscanf() not writing value scaned from file

I wrote some functions.

typedef struct {
    unsigned long long studentID;
    DATE date;
    char address[256];
    unsigned short isInfected;
}NAT;

int ReadAllNAT(NAT** AllNATPtr) {
    FILE* NATSet = NULL;
    NATSet = fopen("NATData", "r");
    int dataNum = 0;
    NAT* AllNAT = NULL;
    if (NATSet != NULL) {
        fscanf(NATSet, "%d\tDataNum", &dataNum);
        AllNAT = (NAT*)malloc(dataNum * sizeof(NAT));
        for (int i = 0; i < dataNum; i++) {
            fscanf(NATSet, "%lld", &AllNAT[i].studentID);
            fscanf(NATSet, "%d-%d-%d", &AllNAT[i].date.year, &AllNAT[i].date.month, &AllNAT[i].date.day);
            fscanf(NATSet, "%d", &AllNAT[i].isInfected);
            fscanf(NATSet, "%s", AllNAT[i].address);
            fscanf(NATSet, "END");
        }
        fclose(NATSet);
        *AllNATPtr = AllNAT;
    }
    return dataNum;
}

int WriteNAT(const NAT* newNAT, const NAT* AllNAT, int dataNum) {
    FILE* NATSet = NULL;
    NATSet = fopen("NATData", "w");
    int isSucceed = 0;
    if (NATSet != NULL) {
        fprintf(NATSet, "%d\tDataNum\n", (dataNum + 1));
        for (int i = 0; i < dataNum; i++) {
            fprintf(NATSet, "ID\t%lld\tDate-y\t%d\tDate-m\t%d\tDate-d\t%d\tAddress\t%s\tI\t%d\tEND\n", AllNAT[i].studentID, AllNAT[i].date.year, AllNAT[i].date.month, AllNAT[i].date.day, AllNAT[i].address, AllNAT[i].isInfected);
        }
        fprintf(NATSet, "ID\t%lld\tDate-y\t%d\tDate-m\t%d\tDate-d\t%d\tAddress\t%s\tI\t%d\tEND\n", newNAT->studentID, newNAT->date.year, newNAT->date.month, newNAT->date.day, newNAT->address, newNAT->isInfected);
        fclose(NATSet);
        isSucceed = 1;
    }
    return isSucceed;
}

I use them to change a file. Those functions can add new line to this file.

2   DataNum
ID  11  Date-y  1   Date-m  1   Date-d  1   Address 1   I   0   END
ID  12  Date-y  1   Date-m  1   Date-d  1   Address 1   I   0   END

The number "2" stands for the number of lines.

But something went wrong. I use debug mode to find the value of the struct. I saw fscan() didn't write the value which scaned from file and return 0. I changed MSVC to MinGW-gcc, but it still doesn't work. How to make fscanf() works properly? Do I need to redesign a new formant of it? Please lend me a hand. I will be very grateful.

How to make "fscanf()" works properly?

(OP used the wrong format, wrong specifiers, %s lacked width & swapped 2 structure members)

Do not use fscanf() to read as it makes error detection and recovery difficult.

Instead use fgets() for all file input to read a line into a string ...

char buf[sizeof(NAT) * 2]; // be generous
if (fgets(buf, sizeof buf, NATSet)) {

... and now parse. To parse the string, one nice way uses sscanf() with " %n" to detect the complete parsing of one line.

  // ID  11  Date-y  1   Date-m  1   Date-d  1   Address 1   I   0   END
  int n = 0;
  sscanf(buf, "ID %llu Date-y %d Date-m %d Date-d %d Address %255s I %hu END %n",
     &AllNAT[i].studentID, &AllNAT[i].date.year, &AllNAT[i].date.month,
     &AllNAT[i].date.day, AllNAT[i].address, &AllNAT[i].isInfected, &n);
  if (n == 0 || buf[n]) {
    printf("Invalid input <%s>\n", buf);
  }

Note: "%255s" will not well parse an address with spaces in it. To handle that, post sample input.