[Boost-users] [Accumulators] Matching via ADL.

In this code sequence: boost::accumulators::accumulator_set< long, boost::accumulators::features< boost::accumulators::tag::sum > > my_acc; long f( ) { using namespace boost::accumulators; return sum( my_acc ); } why do I need a using declaration? Shouldn't sum() be found via ADL? Using Boost 1.39 & MSVC 8. Thanks - Rob.