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?

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