dropzone.js and ASP.NET MVC file posted is null?

I am trying to use dropzone.js to upload images in my ASP.NET MVC app. I am able to set-up the dropzone programatically, click on it, select the image and when I click "Open" in the file dialog, the correct Action is hit in the controller. However, the HttpPostedFileBase always comes back as null so I can't do anything with the image. ON the client-side, however, it shows the image thumbnail correctly, eventhough I can't get it on the server side. This is the HTML: ``` <div style="float:left;margin-right:2px;" id="mainImage"> <img src="/images/AddImage_button.png" class="dz-message" /> </div> ``` This is the js code I call after the doc is ready: ``` var myDropzone = new Dropzone("div#mainImage", { url: "/Market/UploadImage" }); ``` And this is the action call inside of the controller: ``` public ContentResult UploadImage(HttpPostedFileBase imageFile) { if (imageFile == null || imageFile.ContentLength == 0) { //..... } } ``` The action is hit but imageFile is null. Does anyone has any ideas? By the way, the "dz-message" class was added in the image placeholder inside the dropzone because before that it was not clickable. I read it somewhere that was a fix for that issue and it worked. Any ideas why I am getting null for imageFile?