I am trying to add employees data to a text file in c using array of pointer to struct

Question

first, I read all data from a file and put it in an array of pointer to struct and the add function is to add an employees data first last name etc... and then put in a pointer to struct with the data and return a pointer to the data by the function initdata and allocate more space in the heap with realloc then save all the data in the file but when i add a more than 2 or 3 people data the save function crashes i don't know why

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// iam working with an array of pointer to struct
typedef struct
{
    int day, year, month;
} date;

typedef struct
{
    int Id;
    float salary;
    char *f_name, *l_name, *adress, *email, *p_num;
    date * b_date;
} Data;

date* initdate(int day, int month, int year)
{
    date *x = (date*) malloc(sizeof(date));
    x->day = day;
    x->month = month;
    x->year = year;
    return x;
}

Data* InitData(int Id, char *p_num, float salary, char *f_name, char *l_name, char *adress, char *email, int day, int month, int year)
{
    Data *some = (Data*) malloc(sizeof(Data));
    some->adress = (char*) malloc(strlen(adress) + 1);
    some->email = (char*) malloc(strlen(email) + 1);
    some->l_name = (char*) malloc(strlen(l_name) + 1);
    some->f_name = (char*) malloc(strlen(f_name) + 1);
    some->p_num = (char*) malloc(strlen(p_num) + 1);
    some->Id = Id;
    some->salary = salary;
    strcpy(some->adress, adress);
    strcpy(some->f_name, f_name);
    strcpy(some->email, email);
    strcpy(some->l_name, l_name);
    strcpy(some->p_num, p_num);
    some->b_date = initdate(day, month, year);
    return some;
}

//that is the function to read from a file it has no problem  
Data **ReadFile(const char *FileName, int *i)
{
    FILE *x = fopen(FileName, "r");
    if (!x)
    {
        error(FileName);
        return NULL;
    }

    Data *st[100];
    char str[100];
    *i = 0;
    int count = 0;
    while (!feof(x))
    {
        fgets(str, 99, x);
        if (strcmp(str, "\n")) st[(*i) ++] = deserialize(str);
    }

    Data **flu = (Data **) malloc(sizeof(Data*) * (*i));
    int j;
    for (j = 0; j<*i; j++) flu[j] = st[j];
    fclose(x);
    return flu;
}

//and that is the function read a data of an employee to the file which has a problem

int Add_Emp(int *emp_num, Data **emp)
{
    int Id, day, year, month;
    float salary;
    char f_name[35], l_name[35], adress[40], email[40], p_num[30];
    getchar();
    printf("Enter Your First Name: ");
    gets(f_name);
    printf("Enter Your Last Name: ");
    gets(l_name);
    printf("Enter Your address: ");
    gets(adress);
    printf("Enter Your email: ");
    gets(email);
    printf("Enter Your Phone Number: ");
    gets(p_num);
    printf("Enter Your id: ");
    scanf("%d", &Id);
    printf("Enter Your salary: ");
    scanf("%f", &salary);
        printf("Enter The Date of Birth In This Order Day Month Year :");
        scanf("%d%d%d", &day, &month, &year);
    emp = (Data **) realloc(emp, ((*emp_num) + 1) *sizeof(Data*));
    if (emp == NULL) exit(2);
    emp[*emp_num] = InitData(Id, p_num, salary, f_name, l_name, adress, email, day, month, year);
    ++(*emp_num);
    return 1;
}

//and thats the function to save the final file 
void save(Data **x, int n, const char *file_name)
{
    int i;
    FILE *f = fopen(file_name, "w");
    if (!f) error(file_name);
    for (i = 0; i < n; i++)
    {
        char *a = serialize(x[i]);
        fprintf(f, "%s", a);
    }

    fclose(f);
    printf("progress saved \n");
    line();
}
int main()
{
      char F_Name[40];
      int Emp_Num;
      Data **emp;
      while(1){
      printf("Enter File Name:  ");
      gets(F_Name);
      emp=ReadFile(F_Name,&Emp_Num);
      if(emp) break;
      }
    int w;
    do
    {
        line();
        printf("\n1:search For An Employee.\n2:Add An Employees Data.\n3:Delete An Employees Data.\n4:Modify An Employee Data.\n5:Print All The Employees Data.\n6:Save All Your Changes.\n0:exit"); line();
        printf("Enter Your Choice: "); line();
        scanf("%d",&w);
        char l_name[15],FirstName[15];
        int t,Id,m;
        switch (w)
        {
         //  case 1 :   getchar(); printf("Enter The Employee Last Name: ");
            //          gets(l_name);  Search(emp,Emp_Num,l_name);
             //         break;
           case 2 :   Add_Emp(&Emp_Num,emp);tel=0;  break;

        //   case 3 :   getchar(); printf("Enter The Employee First Name: //");
                   //   gets(FirstName); line();
                   //   printf("Enter The Employee Last Name: ");
                   //   gets(l_name);  line(); //Delete(emp,&Emp_Num,l_name,FirstName); tel=0; break;
          // case 4 :  printf("Enter Id Of The Employee");line(); //scanf("%d",&Id);line(); modify2(emp,Emp_Num,Id); tel=0;break;
         //  case 5 :  line();printf("\n1:Sorted By Last Name.\n2:Sorted By //Salary.\n3:Sorted By Date Of Birth.");
                   //  line(); printf("Enter Your Choice: ");  line(); //scanf("%d",&t);if(!strstr(emp[Emp_Nu-1]-//>email,"\n"))strcat(emp[Emp_Num-1]->email,"\n");
                    // Sort(emp,Emp_Num,t); break;
           case 6 :  save(emp,Emp_Num,F_Name); tel=1;  break;
           //case 0 :  if(!tel){printf("All your changes since your last save //will be discarded. \n do you still wish to exit ?\n1.Yes\t2.No");line();
                   // scanf("%d",&m);}else m=1;Quit(Emp_Num,m,emp); break;
          default : fprintf(stderr,"Sorry %d Isn't a Valid Choice",w); break;
        }
    }while(1);
    return 0;
}