Error using boost::bind for subscribe callback

We're getting this compile error followed by many more errors showing attempts to match the subscribe parameters to all possible candidate functions when using boost::bind as a callback for subscribe.

error: no matching function for call to ‘ros::NodeHandle::subscribe(const char [18], int, boost::_bi::bind_t<void, void (*)(const geometry_msgs::WrenchStamped_<std::allocator<void> >&, moveit::planning_interface::MoveGroup&), boost::_bi::list2<boost::arg<1>, boost::_bi::value<moveit::planning_interface::MoveGroup*> > >)’

Our code is as follows. The commented lines show the code which works when the MoveGroup context (object pointer) is not passed.

#include <stdio.h>
#include <boost/bind.hpp>
#include <geometry_msgs/WrenchStamped.h>
#include <moveit/move_group_interface/move_group.h>

using namespace Eigen;
using namespace std;

//void contact_callback(const geometry_msgs::WrenchStamped& msg) {
void contact_callback(const geometry_msgs::WrenchStamped& msg, moveit::planning_interface::MoveGroup &group){
    //if(msg.wrench.force.z > 5) group.stop();
}

int main(int argc, char **argv) {
    ros::init(argc, argv, "get_stiffness");
    ros::NodeHandle node_handle; 
    ros::AsyncSpinner spinner(1);
    spinner.start();
    moveit::planning_interface::MoveGroup group("manipulator");
    ros::Subscriber contact_sub;
    //contact_sub = node_handle.subscribe("/finger1/nano17ft",1,contact_callback);
    contact_sub = node_handle.subscribe("/finger1/nano17ft",100,boost::bind(contact_callback,_1,&group));
    ros::waitForShutdown();
    return 0;
}