文件上载进度事件未触发，但文件上载

I've seen a few posts on here with similar issues, but I can't seem to get this solved. Basically, I have an AJAX file uploader that doesn't seem to call the progress event. The other events fire just fine, and the file uploads exactly as I expect it, but the progress event isn't being called. The javascript is shown below:I've seen a few posts on here with similar issu