Setpoint_velocity/cmd_vel problem

hi everyone,i am new here:). i am building my hexacopter with a cube orange and a rasperry. i have some problems :(.
i would like to control my hexacopter using setpoint_velocity but it seams that didn’t work. i can publish my velocity but nothing happened. why? i can arm and change mode in guided.
Another way to move my copter is to use setpoint_position but i didn’t work ( maybe because i don’t have an echo from local position?)
i am quite desperate:( can you help me?