Antonio, welcome to OAUSA.
I use a Kenwood TM-D710A in my rig connected to a laptop with an internal GPS, running UI-View 32 software. I also have a Lowrance globalmap Baja 540C that connects to the TM-D710A for those occassions my laptop is not in the vehicle, but I want APRS to work. Both work fine, and I have no issues with APRS.
In order to help you to figure out how to resolve the issues you are having, we'll need more info on your system specifics, and your menu settings, especially those in the APRS sub-menu. Ollie (K6JYB) and I both run identical settings - but we had some initial problems, too - so don't feel alone
Once your settings are adjusted properly, you should be good to go.
You didn't mention which GPS did you interface with the TM-D710A to provide location data, and how it's connected. If the GPS is not functioning, or not connected properly (GPS indicator on the upper screen of the D710A is
not flashing), APRS will not work, either.
You probably know this, but the TM-D710A requires an external GPS to provide location information....if you haven't hooked one up, check out the Geen Labs GPS-710 module for the D710A - it mounts directly to the back of the remote head, and requires no additional wiring as it connects in-line...you won't have a map display, but you'll have full-function APRS.
GREEN LABS GPS-710