(a / b) mod p for large a and b

Question

i get stuck in finding $(a / b) \bmod p$
what i did is googled and saw some theories and i did
$(a/b) \bmod p = ((a \bmod p) * (((b^{\,p - 2} \bmod p)) \bmod p)) \bmod p$
where $p$ is prime number $(10^9+7)$

but i am still getting wrong answer.
i used divide and conquer to find $b^{\,p-2}$ as below:

ll m=1000000007;
ll power(ll x,  ll y,  ll m)
{
    if (y == 0)
        return 1;
    ll p = power(x, y/2, m) % m;
    p = (p * p) % m;

    return (y%2 == 0)? p : (x * p) % m;
}

and called the function power(b,m-2,m);
and finally compute the result as ((a%m)*(power(b,m-2,m)%m))%m

but i am still getting wrong answer.
please help me finding what i am doing wrong.
thanks in advance!