[]有时候飘字的时候会在其他地方有一道黑条是什么原因？

//跑马灯 - 底
textDi = new Image(LoadUrl.BASE_PATH + "common/img_paomaDi.png");
textDi.sizeGrid = "5,5,5,5";
textDi.size(580,30);
this.addChild(textDi);
_divElement = new HTMLDivElement();
_divElement.style.fontSize = 18;
_divElement.style.color = "#ffffff";
//_divElement.style.strokeColor = "#34edde";
_divElement.style.wordWrap = false;
//_divElement.style.stroke = 1;
_divElement.style.bold = true;
this.addChild(_divElement);
var ms:Sprite = new Sprite();
ms.graphics.drawRect(0,0,567,32,"#ffffff");
this.mask = ms;