Minified code runs into error

I'm developing a module to recognize simple gestures based on hc-sr04.
Code runs fine, but minified(simple optimization) runs into error, somewhere around calcGesture.

function gesture(trig,echo){
  function Empty(){}
  function gestureArea(min,max){this.min = min;this.max = max;this.active = true;}
  function trigger(){ digitalPulse(trig, 1, 0.01); }
  var riseTime = 0,fallTime = 0,iv,ivDef = 50,clkDef = 0.15;
  var min = 10,max = 100,actArea = "",prevArea = "",lastEnter = 0;
  var callback = {enter:Empty,leave:Empty,click:Empty,move:Empty};
  var areas = {};
  this.setRange = function(mn,mx){min = mn;max = mx;};
  this.setCallback = function(t,f){callback[t] = f;};
  this.addArea = function(name,min,max){ areas[name] = new gestureArea(min,max); };
  this.setAreaStatus = function(name,status){ areas[name].active = status; };
  this.start = function(t){
    ivDef = t || 50;
    clkDef = ivDef * 3 / 1000;
    iv = setInterval(function(){trigger();},ivDef);};
  this.stop = function(){clearInterval(iv);};
  function calcGesture(d){
    var a;
    if(between(min,max,d)){
      a = getArea(d);
      if(a){
        if(actArea === a){
          a = areas[a];
          callback.move("move",actArea,d,(d - a.min) / (a.max - a.min) * 100);
        }
        else{
          if(actArea !== ""){ callback.leave("leave",actArea,d); }
          callback.enter("enter",a,d);
          lastEnter = fallTime; prevArea = actArea;actArea = a;
        }
      }
      else{prevArea = actArea;actArea = "";}
    }
    else{
      if(actArea){
        callback.leave("leave",actArea,d);
        if((fallTime - lastEnter) < clkDef){ callback.click("click",actArea,d); }
      }
      prevArea = actArea; actArea = "";
    }
  }
  function getArea(d){
    for(var a in areas){ 
      if(areas[a].active){
        if(between(areas[a].min,areas[a].max,d)){ return a; }
      }
    }
    return "";
  }
  function between(min,max,value){return (value>min && value<max);}
  setWatch(function(e){riseTime = e.time;},echo,{repeat:true, edge:'rising'});
  setWatch(function(e){
    fallTime = e.time;
    calcGesture(((fallTime - riseTime) * 1000000)/ 57);
  },echo,{repeat:true, edge:'falling'});
}
var g = new gesture(A0,A1);

g.addArea("bottom",10,20);
g.addArea("middle",30,40);
g.addArea("top",50,60);
//g.setCallback("enter",function(a,t,d){console.log(a,t,d);});
//g.setCallback("leave",function(a,t,d){console.log(a,t,d);});
g.setCallback("click",function(a,t,d){console.log(a,t,d);});
//g.setCallback("move",function(a,t,d,p){console.log(a,t,d,p);});