IGate not sending ACK responses consistently

Richard Steele NA9X

Just tinkering a bit... I have a simple IGate setup with an old Kenwood V7a, a Rigblaster Advantage in vox mode and am using UZ7HO sound modem on a PC. 
The system will receive and successfully pass SMSGTE and EMAIL-2 messages from RF to IS from a handheld and a mobile unit. However, it doesn't send out ACK messages when the message originates with my HT but does send out ACKs to messages from my mobile. Is there something obvious I'm missing?

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