Will not key TenTec Omni vii. I use three cables out of digirig, in, out and key

Program set to RTS/COM4, RIG CONTOL, HARDWARE PTT. IF i short key line to rog it keys. If i measure for short or voltage from digirig, nothing. I need a short on key line from digirig. Any suggestions?

Can you please share the screenshot of the Device Manager showing the serial ports and PTT configuration in the digital modes software.