Problème allocation dynamique d'un tableau

#include <stdio.h>
#include <stdlib.h>

typedef struct s_grille {
 int nbl;
 int nbc;
 int **cellules;
} Grille;

void alloue_grille (int l, int c, Grille *g);
void libere_grille (Grille* g);
int main(){
 
 int i,j,c=0;

 int line = 30, col = 50 ;
 Grille *g = malloc(sizeof(Grille));
 alloue_grille(line,col,g);
 

 //remplissage
 for(i = 0; i < line; i++){
  for( j = 0; j < col ; j++){
   g->cellules[j][i] = c++;
  }
 }

 //affichage
 for(i = 0; i < line; i++){
  for( j = 0; j < col ; j++){
   printf("%d  ", g->cellules[j][i]);
  }
  printf("\n");
 }

 libere_grille(g);

 return 0;
}

void alloue_grille (int l, int c, Grille *g){

 int i;
 g->nbl=l;
 g->nbc=c;
 g->cellules = (int**)malloc( c * sizeof(int*));
 for(i=0;i<c;i++) g->cellules[i] = (int*)calloc(l,sizeof(int*));
}

void libere_grille (Grille* g){

 int i;
 for(i=0;i<g->nbc;i++) free(g->cellules[i]);
 free(g->cellules);
 free(g);

}

==7077== HEAP SUMMARY:
==7077==     in use at exit: 0 bytes in 0 blocks
==7077==   total heap usage: 53 allocs, 53 frees, 13,440 bytes allocated
==7077== 
==7077== All heap blocks were freed -- no leaks are possible
==7077==