MAV_CMD_WAYPOINT_USER_1 unsupported by the vehicle

Hi, i’m faced with such issue: when i send mavlink_mission_item_t packet with command = MAV_CMD_WAYPOINT_USER_1 vehicle responses with MAV_MISSION_UNSUPPORTED. Why so?

I got the same problem when I try to send MAV_CMD_USER_!. do you finally solve it?

I apologize for waiting for an answer. We have it sent, but we did without it.