canvas.toDataURL is not can work

[April-D-phil]

i want to use make a image and append in my dom, but not work in IE8. what's the problem?
...
var image = canvas.toDataURL("image/png");
var img = document.createElement("img");
img.src = image;
img.width = canvas.width;
img.height = canvas.height;
$("#id").append(img);
...