Good day Gilbert,
Thank you for your reply.
I would just like to add additional information (forgot to include them last night):
1. used the latest stable release (1.10.1)
2. same behavior observed in windows xp 32bit (vs2010) and centos 6.4 32bit/64bit.
3. dissector dissects successfully.
4. protocol seems to be registered as it can be seen in 'Analyze'->'Enabled Protocols'
5. filter name shows in the drop down selection in the display filter combo box
I also just ran 'tshark -G protocols' and the protocol is indeed known.
Perhaps it is as you say that the protocol is matching something else.
Haven't yet tried dftest and will try it as time permits.
Thank you,
David