百度地图自定义覆盖物

Question

var mp = new BMap.Map("allmap",{minZoom:16,maxZoom:19,enableMapClick: false});
    mp.centerAndZoom(new BMap.Point(114.324421,30.534198), 15);
    mp.enableScrollWheelZoom();
    
    // 复杂的自定义覆盖物
    $.get('/ph/Api/get_ban_map_point',function(res){
        res = JSON.parse(res);
        var aDate = res.data.point.length;
        console.log(res);
        for(var i=0;i<aDate;i++){            
    ComplexCustomOverlay.prototype = new BMap.Overlay();
    ComplexCustomOverlay.prototype.initialize = function(map){
      this._map = map;
      var div = this._div = document.createElement("div");
      div.style.backgroundColor = "#2d69f9";      
      div.style.color = "white";
      div.style.width = "110px";
      div.style.padding = "5px";
      div.style.lineHeight = "18px";
      div.style.whiteSpace = "nowrap";
      div.style.MozUserSelect = "none";
      div.style.fontSize = "12px"
      var span = this._span = document.createElement("span");
      div.appendChild(span);
      span.appendChild(document.createTextNode(this._text));      
      var that = this;

      var arrow = this._arrow = document.createElement("div");
      arrow.style.width = "0px";
      arrow.style.position = "absolute";
      arrow.style.height = "0px";
      arrow.style.borderLeft = "10px solid transparent";
      arrow.style.borderRight = "10px solid transparent";
      arrow.style.borderTop="10px solid #2d69f9"
      arrow.style.left="20px";
      arrow.style.top="25px";
      div.appendChild(arrow);
     
      div.onmouseover = function(){
        this.style.backgroundColor = "#ff6400";
        arrow.style.borderLeft = "10px solid transparent";
        arrow.style.borderRight = "10px solid transparent";
        arrow.style.borderTop="10px solid #ff6400" ;
      }

      div.onmouseout = function(){
        this.style.backgroundColor = "#2d69f9";
//      this.style.borderColor = "#BC3B3A";
        this.getElementsByTagName("span")[0].innerHTML = that._text;
//      arrow.style.backgroundPosition = "0px 0px";
          arrow.style.borderLeft = "10px solid transparent";
          arrow.style.borderRight = "10px solid transparent";
          arrow.style.borderTop="10px solid #2d69f9" ;
      }

      mp.getPanes().labelPane.appendChild(div);
      
      return div;
    }
    ComplexCustomOverlay.prototype.draw = function(){
      var map = this._map;
      var pixel = map.pointToOverlayPixel(this._point);
//    this._div.style.left = pixel.x - parseInt(this._arrow.style.left) + "px";
//    this._div.style.top  = pixel.y - 30 + "px";
    }
   
     
    var myCompOverlay = new ComplexCustomOverlay(new BMap.Point(res.data.point[i].BanGpsX,res.data.point[i].BanGpsY), res.data.point[i].BanID);
    mp.addOverlay(myCompOverlay);
   
        }
    })//get    
    function ComplexCustomOverlay(point, text){
      this._point = point;
      this._text = "编号:"+text;  
    }

为什么位置都凑到一起去了。