Well I designed and built a triac light driver, right now I am just interfacing it with a led effects controller. Outputs are 5v, optos moc3021, triac bta06-600, resistors 200 ohms. I am getting no effects on the lights (but no smoke either)http://www.pcboard.ca/kits/ledfx/
Have you tested the TRIAC driver alone? i.e. Connect 5V to an input to see if the light comes on?
What kind of christmas lights are you using? (Regular 'ol incandescent or LED?) LEDs might have some sort of power supply that doesn't "like" being switched on & off rapidly.
Hi mrgizmo
Seems that you need to ground the inputs. As your anodes are connected to +5v.
if you are going to use an Arduino you could try the blinkie sketch on one input to see if it works.
But remember you have to sink the inputs, or ground.
A triac needs a minimum current to getting to work. Try putting a 50W lamp in the circuit and put your led driver circuit that you normally connect to the mains in parallel with it.