You most likely only have the cable plugged into the side of the nuvi going to your OT2.
On a non-modified normal NUVI350 you need both the data cable plugged in the side going to your OT2, as well it needs to be docked in its cradle with the power plug connected to the rear of the dock providing it with power.
--- In email@example.com, "rooster4bravo" <kd0ofx@...> wrote:
> I've searched this phrase and, and while I see similar issues, I haven't found the solution. Maybe someone can point me in the right direction. I have a Nuvi 350 connected to an OT3m with the 010-10813-00 cable. I get a message on the Nuvi that says "This accessory is not supported."
> What am I doing wrong?