function "hover" on LayerSlider?

i tried to
– set the #ID “first” in the slide option of layerslider
– i find out that the item class is “.ls-linkto-2”
– i add this to custom css

#first.ls-linkto-2 {
	opacity:0.25;
}

and works, but when i add hover

#first.ls-linkto-2 li img:hover {
	opacity:0.25;
}

that doesn’t work, please help me