Exception thrown at 0x53730ED0 (ucrtbased.dll) in 0xC0000005: Access violation reading location 0xCDA9C0F0

I am loading data into a struct array.  I am using while loop to prompt for first and last name.  The user should be able to exit the loop by enter a '0' in either First Name or Last Name.  I getting and exception error.  I am a newbie, so forgive me for not choosing the most efficient approach.  Welcome any recommendations
Please tell me what I am doing wrong.  I am encountering this error:
Exception thrown at 0x53730ED0 (ucrtbased.dll) in grader.exe: 0xC0000005: Access violation reading location 0xCDA9C0F0

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_STUDENTS 30

struct student
{
  char fname[15];
  char lname[10];
  float percentGrade;
  char letterGrade;
};
typedef struct student STUDENT;

void enterStudents(STUDENT [], int *);

main()

{

    STUDENT students[MAX_STUDENTS];
    int studentCount = 0;
      
      enterStudents(students, &studentCount);

      
    return(0);
}

void enterStudents(STUDENT students[], int * ptr_studentCount)
  {
     

    /*  Prompt for initial input  */
    printf("\n Enter First Name or (0) to exit :");
    scanf(" %14[^\n]", students[*ptr_studentCount].fname); //adding the space and deleting the s
    fflush(stdin);
                                                           /*  Prompt for initial input  */
    printf("\n Enter Last Name or (0) to exit :");
    scanf(" %9[^\n]", students[*ptr_studentCount].lname); //adding the space and deleting the s
    fflush(stdin);
   
   
    while (strcmp(students[*ptr_studentCount].fname,"0") || strcmp(students[*ptr_studentCount].lname, "0") )
    {
           
      // Prompt for first name
      printf("\n Enter Student First Name or (0) to exit :");
      scanf(" %14[^\n]", students[*ptr_studentCount].fname);
      fflush(stdin);

      /*  Prompt for last name  */
      printf("\n Enter Student Last Name or (0) to exit :");
      scanf(" %9[^\n]", students[*ptr_studentCount].lname);
      fflush(stdin);

      *ptr_studentCount++;
     
    }
    system("pause");
 }
 
 Exception thrown at 0x53730ED0 (ucrtbased.dll) in grader.exe: 0xC0000005: Access violation reading location 0xCDA9C0F0.