Key Press Triggers in Layers

Hi,

I am trying to add key press triggers for Next and Previous slide options in Storyline 360.

This works well when moving from slide to slide, but I would also like to be able to use the Next and Previous options for moving between layers.

What I have found is that if a key press trigger is used on the base layer it can't also be used on the layers - so if I have the left arrow triggering previous slide on the base layer, a trigger using the left arrow to show a different layer on one of the layers doesn't do what the trigger states but moves to the previous slide.  Likewise, if I have the right arrow set to show the next layer, this works well for all of the layers but doesn't work on the last layer to show next slide.

Is there a slide/layer setting that I am missing that will allow Next and Previous key triggers to work seamlessly between layers and slides?

Thanks :-)