Radius unable to disconnect hotspot user through port 1700 -

I am trying to get freeradius radclient to disconnect a hotspot user on mikrotik board. I’m getting as far as successfully sending a disconnect packet using radclient and getting a response back:

>radclient -x -f packet.txt 11.0.0.239:1700 disconnect 2ndave_rad
ius

Sending Disconnect-Request of id 88 to 11.0.0.239 port 1700
Acct-Session-Id = “80500030”
User-Name = “00:18:DE:A4:95:8D”
NAS-IP-Address = 11.0.0.239

rad_recv: Disconnect-NAK packet from host 11.0.0.239:1700, id=88, length=42
Error-Cause = Unsupported-Extension
NAS-Identifier = “MikroTik”
NAS-IP-Address = 11.0.0.239[/b]

Why does Mikrotik give an error of “Unsupported Extension”? If I look in Mikrotik under Radius > Incoming, it shows the requests coming through, but no Acks, only Naks.

Please help!