开发版本，模拟器上头像显示正常，真机头像刷不出来

index.js代码片段：

var headImage = wx.createImage();

headImage.toY = i;

if(rankDic.avatarUrl != ""){

headImage.src = rankDic.avatarUrl;

}else {

headImage.src = "res/raw-assets/resources/rank/defaulthead.png";

}

headImage.onload = function (event) {

var img = event.target;

var r = 33;

var lineTop = 60-r;

logD("headImage . toY: "+i);

context.drawImage(img,73,img.toY*117+lineTop,r*2,r*2);

};

报错信息：

[wxgl] invalid drawimage 4816997536

头像显示不出来，http地址在浏览器上访问是可以的