c++11 using lambda sort vector keeping track of indices

I have tried to apply this solution using c++11 (I am using gcc-4.8.2)

// sort algorithm example
#include <iostream>     // std::cout
#include <algorithm>    // std::sort
#include <vector>       // std::vector

using namespace std;

vector<size_t> sort_indexes(const vector<float> &v) {

  vector<size_t> idx(v.size());
  for (size_t i = 0; i != idx.size(); ++i) idx[i] = i;

  sort(idx.begin(), idx.end(),
       [&v](size_t i1, size_t i2) {return v[i1] < v[i2];});

  return idx;
}

int main () {

  std::vector<float> w(4, 0.2f);
  w.push_back(0.3f);

  std::vector<size_t> idx = sort_indexes(w);

  // print out content:
  std::cout << "ordering:";
  for (std::vector<size_t>::iterator it=idx.begin(); it!=idx.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';

  return 0;
}

but I get a compiling error saying:

error: no matching function for call to ‘sort(std::vector::iterator, std::vector::iterator, sort_indexes(const std::vector&)::__lambda0)’ [&v](size_t i1, size_t i2) {return v[i1] < v[i2];});

error: template argument for ‘template void std::sort(_RAIter, _RAIter, _Compare)’ uses local type ‘sort_indexes(const std::vector&)::__lambda0’

I would appreciate any help :-)