TCP Socket Client Error 16#11

Hi,
I am using 1756-L71 and 1756-EN2TR to communicate with ABB PickMaster, robot application running on industrial PC, via TCP Socket Client.
I create the socket and open the connection with no errors but when I write some data using WriteSocket message I get an error code of 16#11 (extended error 16#00).
Looked through various documents and Rockwell knowledge base and cannot find this error code defined.
Anybody else had this error code or have any ideas?

I don't know about the error but I would use Wireshark between the 2 devices to see what's happening.

Page 49 lists the error codes: http://literature.rockwellautomation.com/idc/groups/literature/documents/at/enet-at002_-en-p.pdf

Thanks for the advice Epy,
I will try Rockwell once I am back within my support hours in the morning and if I do not get any joy there I will try as you suggest.
It is a weird one because the software I am communicating with gets the message and responds correctly even though I get an error on the write.

I have already checked page 49.
If you look there is no error code 16#11, it jumps straight from 16#0d to 16#13.