wireshark and single byte multicast error

[Skunk Worx]

Hi,

I've been practicing my multicast socket programming and noticed if I 
send a single byte over multicast, and monitor via wireshark, I see a 
message in the top pane :

Destination port: <port>[Malformed Packet]

...and in the lower pane :

[Malformed Packet: DCP (ETSI)]

...instead of :

Data (1 byte)

...which is what I expected.

The packet length and checksum are ok. The packet gets read and the byte 
is displayed at the receiver.

Sending more than one byte is ok, data bytes are reported, no error shown.

Is it illegal to send one byte over multicast?

---
John