I'm using OSDK ROS 4.1.0 and trying to get camera image data with m300 in ROS

I executed launch file with ' roslaunch dji_osdk_ros dji_vehicle_node.launch '
then i can find topics like /dji_osdk_ros/stereo_240p_down_back_images
but i couldn't find any signals about that topic

I saw that i have to call setup_camera_stream service
but when i  execute -> rosservice call setup_camera_stream  "cameraType: 1 start: 1"
and I get an error like -> ERROR: service [/setup_camera_stream] responded with an error:

please help me what i to do
I am beginner about programming and m300
If you solve my problem, i will very grateful about you and pray everyday for you

i am also looking for a help in this question ssss