I'm trying to replace a dumb three way dimmer with the Kasa three way dimmer kit (KS230). It is in the same box as an existing Kasa single pole dimmer. The old setup shared the load line with the single pole. When putting in the main switch, I connect the load as before and to the neutral. Before even connecting traveler, I hear the switch clicking a few times, and then fast flashing red light. Tried doing this with two switches from different sets, with the same result. Any ideas?

First picture is the old configuration...dumb switch on the right with the black load shared with the smart dimmer on the left. 

Second picture shows plugging in Kasa three way dimmer...load shared in same manner and neutral also shared. Travelers not connected. Blinking doesn't go away if I connect travelers.