Help with Slider Triggers

Hi,

I need some help with creating the appropriate triggers for my slider (on slide 2 of this project: https://360.articulate.com/review/content/53673d77-d364-4bec-9c32-eaa3c51714fa/review)

I created 3 layers: one with a "pebble" thumb, one with a "stone" thumb, and one with a "boulder" thumb. Right now, my triggers say to show the pebble layer when the slider moves to value 0 and to show the boulder layer when the slider moves to value 10. It kind of works, but then the thumb/layers start changing when they're not supposed to. Can you help me refine this?

Thanks for your time!