Can't get my PC to connect to my APM

Hey folks,

Built a quadcopter with APM 2.6, GPS, Telemetry, etc. Got my USB/Antennae/Tx connected to my laptop, and the Rx connected to the Telem port on my APM.

Using Mission Planner, with the COM 4 selected which shows the USB driver I downloaded. Using the 3DR setup, I try and connect to my remote radio and it keeps failing. Yes I have the baud rate set at the correct rate.

Anything else I need to look at??

State of green LEDs on both units?
How it fails (message)?