Halloween 2017: Halloween overlay for Landscape Lighting

So I thought it would be awesome to do something with my landscape lighting for halloween. They are 12V lights and I was hoping to use a 12v controller to do a flicker or some kind of dimming/surging look to them.

I picked up this 12v controller thinking I could just put it inline but so far that hasn't worked. I'm thinking its due to the lack of polarity in the 12v lighting wire.

Anyone done something like this before and have any advice?

EDIT - Might have figured out my issue, think it is 12v AC and not 12v DC output.

So I thought it would be awesome to do something with my landscape lighting for halloween. They are 12V lights and I was hoping to use a 12v controller to do a flicker or some kind of dimming/surging look to them.I picked up this 12v controller thinking I could just put it inline but so far that hasn't worked. I'm thinking its due to the lack of polarity in the 12v lighting wire.Anyone done something like this before and have any advice?EDIT - Might have figured out my issue, think it is 12v AC and not 12v DC output.