I would like to create a thread group for my "worker objects" like: 

std::vector< worker<T,D> > l_worker;
boost::thread_group l_threads;
for(std::size_t i=0; i < p_threads; ++i) {
l_worker.push_back(  worker<T,D>(p_iteration, p_stepsize, m_derivation, m_optimize, m_static, p_batch)  );
        l_threads.create_thread(  boost::bind( &worker<T,D>::optimize ), l_worker[i]  ); (*)

I get a compiler error at (*) on boost/bind/bind.hpp: 
In instantiation of 'boost::_bi::result_traits<boost::_bi::unspecified, void (worker<double, 2ul>::*)()>':
error: 'void (worker<double, 2ul>::*)()' is not a class, struct, or union type

boost/bind/bind_template.hpp:15:   instantiated from 'boost::_bi::bind_t<boost::_bi::unspecified, void (worker<double, 2ul>::*)(), boost::_bi::list0>'

The variables T is a typename and D is std::size_t > 0

How can I bind my template object (<doube, 2>) to the create_thread methode?