PTT not engaging with APRS droid

I have the Digirig hooked up to my android phone, and am running APRS Droid. I know that at least the audio out part of the setup works, as if I hold the PTT button on my UV5R, it will send the packet(and can be heard on another HT). But I am unable to get it to engage the PTT for me. I know in direwolf and other progs, you have to tell it how to do that. I don’t see such a thing in APRS droid. What am I missing here? I know it is all wired up right, as I can send PTT fine from Direwolf on my PC.

For PTT transceivers not capable of CAT control, Digirig uses RTS signal of the serial port as a trigger. The software must support this option. Here is the list of the Android apps that does it:

As a fallback method where it is not supported, you can use the VOX feature of your transceiver.