How can I create a new waypoint during the auto flight?

ArduCopter Copter 4.0
1

Hi guys!

I trying delete and creation a new mission during the auto flight mode.
I use this metods:
mission.stop();
mission.clear();
mission.start_or_resume();

And then I create a new command with the location specified as follow:
//First wp
cmd.id = MAV_CMD_NAV_WAYPOINT;
cmd.p1 = 0;
cmd.content.location = inertial_nav.get_position();
cmd.content.location.offset(x, y);
cmd.index = 0;
cmd.create = true;
copter.wp_nav->set_wp_destination(cmd.content.location);
mission.add_cmd(cmd);

       //Second wp
        next_wp.id = MAV_CMD_NAV_LAND;
        next_wp.p1 = 0;
        next_wp.content.location = location;
        next_wp.index = 4;
        copter.wp_nav->set_wp_destination(location);
        mission.add_cmd(next_wp);

But the problem is that it skips the first created wp and goes straight to the second. How do I make him follow both wp? I try change the index equal 0 in both.

Thanks!