Thread: strcpy results null

Code:

int main() {    char x[] = "Happy Birthday to You";
    char y[25];
    char z[15];


    printf( "%s%s\n%s%s\n",
 "The string in array x is: ", x,
 "The string in array y is: ",strcpy_s( y, x ) );
    strncpy_s(z,x,14);
    z[14]='\0';
    printf("\nz is %s",z);


    _getch(); 
    return 0; 
}

why is y printed as <null>?