Vector sorting of character vectors with qsort

The following program is not ordering the vector of chars vectors correctly, but I don't know why. Maybe it's my helper function "cmpstr" that is not returning the right value in some cases, or my qsort call...What's wrong?

#include <iostream>
#include <cstdlib> //qsort
#include <cstring> //strcmp
using namespace std;

int cmpstr(const void* a, const void* b){ // função auxiliar do qsort
    const char* aa = (const char*)a;
    const char* bb = (const char*)b;
    return strcmp(aa, bb);
}

char equipe[1000][5000][50]; //array de arrays de arrays de caracteres

int main()
{
    int qtd_alunos, qtd_times, qtd_membros;
    cin>>qtd_alunos>>qtd_times;
    qtd_membros = qtd_alunos/qtd_times;

    for(int j=0; j<qtd_membros; j++){   //recebe nomes
        for(int i=0; i<qtd_times; i++){
            cin>>equipe[i][j];
        }
    }

    for(int j=0; j<qtd_times; j++){  //ordena cada equipe [deveria ordenar]
        qtd_membros = qtd_alunos/qtd_times;
        qsort(equipe[j], qtd_membros, sizeof(char*), cmpstr);
    }
    for(int i=0; i<qtd_times; i++){  //exibe a composição de cada equipe
        cout<<"Time "<<i+1<<'\n';
        qtd_membros = qtd_alunos/qtd_times;
        for(int j=0; j<qtd_membros;j++){
            cout<<equipe[i][j]<<'\n';
        }
        cout<<'\n';
    }
    return 0;
}