COMMAND_ACK result : 3 error

I have been trying to set FENCE_CIRCLE_EXCLUSION points using pymavlink library on Python. However when i read the ack message it says it is unsupported. I have set FENCE_ENABLE parameter as 1 and enabled MAVLink signing on Mission Planner.
Here my code is:
from pymavlink import mavutil

iha = mavutil.mavlink_connection(‘tcp:127.0.0.1:5762’)

x= -35.35832620
y= 149.16626930
r= 100

iha.mav.command_long_send(
iha.target_system, iha.target_component,
mavutil.mavlink.MAV_CMD_NAV_FENCE_CIRCLE_EXCLUSION,
0, frame
0, #target_system
0, #target_component
0, #idx
0, #count
x, #lat
y, #lon
r radius
)

ack_msg = iha.recv_match(type=‘COMMAND_ACK’, blocking=True)
print(ack_msg)

and the Result ;
COMMAND_ACK {command : 5004, result : 3, progress : 0, result_param2 : 0, target_system : 255, target_component : 0}