Z-Index Issue with HTML5 Canvas on IE

I'm trying to use the HTML5 Canvas Element with IE. I'm using ExCanvas which seems to be working ok so far. The triangle I created looks the way I want, but the stacking order varies in IE.

In Firefox, the canvas element appears below the intended target (being that the z-index of target is 21 and the z-index of the div with my canvas element is 20)开发者_开发知识库, which is the way I want it to work. However, in IE6 and IE7, the canvas element appears above.

The two divs have the 'position' css element set up: one is absolute and one is relative. Also, the canvas div is just before the closing body tag, while my target is well nested somewhere above it.

Does IE simply disregard z-index for positioned elements?!