Error: Failed to execute 'toDataURL' on 'HTMLCanvasElement'

[dpz3579]

i tries to save the Image created in canvas,

but it gives me error as :
Error: Failed to execute 'toDataURL' on 'HTMLCanvasElement'

mycode is as follows :

var canvasMemDOM =$('<canvas>');
var canvasMem=canvasMemDOM.get(0);

$(canvasMemDOM).attr('width', imageWidth+"px");
$(canvasMemDOM).attr('height', imageHeight+"px");

var ctxMem=canvasMem.getContext("2d");
ctxMem.drawImage(img, 0, 0, imageWidth, imageHeight);
ctxMem.drawImage(canvas, 0, 0);

canvasImageUrl = canvasMem.toDataURL();

i get error at last line..

canvasImageUrl = canvasMem.toDataURL();

[gsadhas]

set crossOrigin = "Anonymous" for the img