MAV_CMD_DO_CHANGE_SPPED Command

Hi everyone. I am sending this command to my Quadcopter with the MAVLink command over the microprocessor. But nothing is changing. Is there something wrong? Can you help me?

Here is my code;

mavlink_message_t msg;
uint8_t buf[MAVLINK_MAX_PACKET_LEN];

uint8_t _system_id = 255;
uint8_t _component_id = 2;
uint8_t _target_system = 1;
uint8_t _target_component = 0;

float param1 = 1;
//float param2 = hız;
float param3 = 0;
float param4 = 0;
float param5 = 0;
float param6 = 0;
float param7 = 0;

uint16_t CMD_LONG_command = MAV_CMD_DO_CHANGE_SPEED;
uint8_t CMD_LONG_confirmation = 0;

mavlink_msg_command_long_pack(_system_id, _component_id, &msg, _target_system, _target_component, CMD_LONG_command, CMD_LONG_confirmation, param1, param2, param3, param4, param5, param6, param7);