PSET3 -Tideman - lock_pairs

Question

I'm doing tideman and I can't understand where is the problem: my code seems to be working but the test says that it does not.

I will share a bit of my code:

int count = 1

void lock_pairs(void)
{
    int users[pair_count];

     for (int k = 0; k < pair_count; k++)
    {
        users[k] = -1;
    }
    for (int i = 0; i < pair_count; i++)
    {
        if (check(i, users))
        {
            locked[pairs[i].winner][pairs[i].loser] = true;
        }
    }
}

bool check(int n, int users[])
{

    bool check1 = true;
    bool check2 = true;

    for (int i = 0; i < count; i++)
    {
        if (pairs[n].winner == users[i])
        {
            check1 = false;
            break;
        }
        else if (pairs[n].winner != users[i] && count - 1 < pair_count)
        {
            users[count - 1] = pairs[n].winner;
            count++;
            break;
        }
    }

    for (int j = 0; j < count; j++)
    {
        if (pairs[n].loser == users[j])
        {
            check2 = false;
            break;
        }
        else if (pairs[n].winner != users[j] && count - 1 < pair_count)
        {
            users[count - 1] = pairs[n].loser;
            count++;
            break;
        }
    }

    if (check1 == false && check2 == false)
    {
        return false;
    }
    else
    {
        return true;
    }
}

The output of test: 
:) lock_pairs locks all pairs when no cycles
:( lock_pairs skips final pair if it creates cycle
    lock_pairs did not correctly lock all non-cyclical pairs
:) lock_pairs skips middle pair if it creates a cycle

I would be so thankful for help.