Subscribe to SYSTEM dbus

I am trying to subscribe to system bus messages, but it won't show any message. Could you help me?

This is the code I am using:

from jeepney import DBusAddress, new_method_call, MatchRule
from jeepney.io.blocking import open_dbus_connection

connection = open_dbus_connection(bus='SYSTEM')
sleep_match = MatchRule(type="signal")

connection.send_and_get_reply(
    new_method_call(
        DBusAddress("/org/freedesktop/DBus", "org.freedesktop.DBus"),
        "AddMatch",
        "s",
        (sleep_match.serialise(),)
    )
)

while True:
    message = connection.receive()
    print(message)