[Dx4win] Keying MMTTY

[Bud Governale, W3LL]

I'm trying to get DX4WIN to key MMTTY on my IC-7000.
When clicking on a DX4WIN macro RTTY button, I can hear the tones playing but the Icom IC-7000 is not being keyed.

I have the path to the MMTTY executable set in the DX4WIN RTTY preference window.

I can open the MMTTY program and send RTTY FSK directly from MMTTY. This indicates that the two transistor FSK keying 
cable (PTT and FSK) is functioning properly thru its com port.
If DX4WIN is open at the same time then the MMTTY program cannot open its com port. I have to close DX4WIN to use MMTTY 
as a stand alone program.

I can send CW properly in DX4WIN thru the FSK keying cable com port.
I don't understand why DX4WIN cannot key MMTTY.

What am I doing wrong?

73,

Bud W3LL
w3ll at arrl.net