[Ham-Mac] new Microham USB interface and CocoaModem

[EZ Rhino]

Hello group:

Just got my MicroHam USB Interface II.  Using 746Pro.  I've used  
CocoaModem before using only cables (no interface.)  But for the life  
of me,  I can't get it to trigger the radio PTT to transmit on PSK.   
If I go to the CocoaModem config window in PSK, I see the drop down  
box to select the type of TX PTT.  One of them is "Microham", but it  
is grayed out and I can't select it.  (The only other non-grayed out  
options are VOX and MLDX; neither of which work).  What am I doing  
wrong?

Chris
KF7P