[WriteLog] COM 5 CW keying problem

[Ronald Lodewyck]

Help!
 
Having trouble getting new homebrew CW keying interface to work with Writelog.  
 
Problem:
No CW keying on COM 5 if COM6 = Rig = Elecraft K3.
Keys CW OK on COM5 DTR if No Rig is selected.
 
Details:
COM5 and COM6 are Edgeport/4 USB to Serial adapter.
DTR is keyed via an optoisolator.
DXLabs works perfectly with rig=K3 on COM 6 and CW keying on COM 5.
Writelog controls K3 AOK on COM6 whether CW port set to COM 5 or not.
If I set CW port to COM 5 and NO RIG selected, Writelog keys CW just fine.
But, if I then set COM 6 to Rig = Elecraft K3, transmit light comes on but no CW keying.
I changed to use a separate Prolific USB to Serial adapter for rig control on COM 3 and get same result:
 i.e. No CW keying on COM 5 if rig selected on COM3, CW keying on COM 5 works fine if I select NO RIG on COM 3 (or any other COM port).
All other control signals on COM 5 are left floating - they are not connected to anything.
 
I have used Writelog a long time, and built many CW keying circuits over the years and can't recall ever having a problem with any of them.  Is this a Writelog / USB-Serial issue?
 
Thanks for any help.
73,
Ron N6EE