ncurses' printw() doesn't work

ncurses' printw() doesn't work

i filled a matrix with strings from a file, that printf() see correctly,
but printw() doesn't seem to agree with the rest of the code. it works
with normal strings, but with strings from that matrix, it doesn't work.
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <ncurses.h>
int main (int argc, char const *argv[])
{
char** matrice = malloc(sizeof(char*)*51);
size_t nbytes;
int i = 0, j = 0;
FILE* lab = fopen(argv[1], "r");
while((getline(&matrice[i], &nbytes, lab) != -1))
{
i++;
}
printf("%s", matrice[0]);
getchar();
initscr(); /* Start curses mode */
cbreak(); /* Line buffering disabled */
keypad(stdscr, TRUE); /* We get F1, F2 etc.. */
noecho(); /* Don't echo() while we do getch */
printw(matrice[0]);
printw("dummy line"\n);
refresh();
getch();
endwin();
return EXIT_SUCCESS;
}