python 3.x – python3 scapy IndexError: Layer [Radius] not found


I’m trying to decode RADIUS packets that sends from Mikrotik via IPFIX and then get details about IP addresses and usernames, so i choose scapy to do that.
this is my code:

from pyrad.packet import Packet
from pyrad.dictionary import Dictionary
from scapy.all import sniff,Radius
def parse_packet(packet):
    radius_packet = str(packet(Radius))
    pkt = Packet(packet=radius_packet, dict=Dictionary("dictionary"))

    for key, value in pkt.iteritems():
        attr =  pkt._DecodeKey(key)
        value = pkt.__getitem__(attr)
        print (attr, value)

sniff(iface='eth0', prn=parse_packet, filter="udp", store=0)

then i got an error when running script:

sudo python3 service.py 
Traceback (most recent call last):
  File "service.py", line 15, in <module>
    sniff(iface='eth0', prn=parse_packet, filter="udp", store=0)
  File "/usr/lib/python3/dist-packages/scapy/sendrecv.py", line 972, in sniff
    sniffer._run(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/scapy/sendrecv.py", line 925, in _run
    session.on_packet_received(p)
  File "/usr/lib/python3/dist-packages/scapy/sessions.py", line 47, in on_packet_received
    result = self.prn(pkt)
  File "service.py", line 7, in parse_packet
    radius_packet = str(packet(Radius))
  File "/usr/lib/python3/dist-packages/scapy/packet.py", line 1171, in __getitem__
    raise IndexError("Layer (%s) not found" % lname)
IndexError: Layer (Radius) not found

how i can fix it?