[RTTY] MMTTY and USB/COM port problem

[Barry]

Hi all.
I recently replaced my shack computer and radio due to lightning 
damage.  I finally got around to wiring up the DIN plug for RTTY and 
it's not working.

I'm using MMTTY in FSK mode with an IC7800.  The computer is a Dell 
Inspiron laptop (XP Home) using a USB to COM port converter.  The COM 
port works fine on CW (with Writelog) and closes the PTT in RTTY, but 
I'm not getting the tones shifting.  All I hear is a clicking under the 
single tone when in monitor mode.  Any ideas?

Tnx,
Barry W2UP