!!Solved!! After Trying all the night I've made it...
Console.print(this.getValue());
var interValueA = this.getValue()/120;
Ambience.setAttribute(Ambience.WetLevel, interValueA);
Now, the moment that i raise the slider, the wet level of the reverb rises. Thanks @Lindon , the code was perfect. Just that i didn't know how to implement it in this scenario. Totally new to coding/scripting so this achievement means a lot to me.