Word Counting wrong answer

http://www.codechef.com/problems/WCOUNT/

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace WordCounting
{
    class MainClass
    {
        private static int _module = 1000000007;
        private static long[] _cache = new long[501];
        private static long[] _powersOf2 = new long[30];

        static void Main(string[] args)
        {
            _cache[0] = 1;
            _cache[1] = 1;

            var words = new List<string>();
            var count = int.Parse(Console.ReadLine());
            for (var i = 0; i < count; i++)
                words.Add(Console.ReadLine().Trim());

            foreach (var item in words)
                Console.WriteLine(Variants(item));

        }

        static Dictionary<char, int> GetFreq(string word)
        {
            var result = new Dictionary<char, int>(26*2);
            foreach (var c in word.ToCharArray())
            {
                if (result.ContainsKey(c))
                    result[c]++;
                else
                    result.Add(c, 1);
            }
            return result;
        }

        static long Variants(string word)
        {
            long result = 1;
            var l = word.Length;
            var stat = GetFreq(word);

            var current = GetDeviders(stat);

            result = Fact(l);
            var inv = Inverse (current);
            //Console.WriteLine ("inv fact {0}={1}", current, inv);

            result = result * inv;

            return result % _module;
        }

        static long Fact(int n)
        {
            if (_cache[n] == 0)
            {
                _cache[n] = (Fact(n-1) * n) % _module;
            }
            return _cache[n];
        }

        static long Inverse(long value)
        {
            _powersOf2 [0] = 1;
            _powersOf2 [1] = value % _module;
            //_powersOf2 [2] = (value * value) % _module;

            for (var i = 2; i < _powersOf2.Length; i++) 
            {
                _powersOf2 [i] = (_powersOf2 [i - 1] * _powersOf2 [i - 1]) % _module; 
            }

            var pointer = _module - 2;
            long result = 1;

            // a inverse = a in power of m - 2


            var bits = new BitArray (BitConverter.GetBytes (pointer));

            for (var i = 0; i < _powersOf2.Length; i++) 
            {
                if (bits [i]) 
                {
                    result *= _powersOf2 [i];
                    result = result % _module;
                }
            }

            return result % _module;
        }

        static long GetDeviders(Dictionary<char, int> stat)
        {
            long result = 1;
            foreach (var item in stat)
            {
                if (item.Value == 1)
                    continue;
                else
                {
                    result = (result * Fact(item.Value)) % _module;
                }
            }
            return result % _module;
        }
    }
}