Even I was facing a problem , The value was null in image at
public ActionResult UploadPlotImadge(HttpPostedFileBase image)
Earlier I didn't add [AcceptVerbs(HttpVerbs.Post)] which I added. Even after adding it, it didn't work because the second part I was missing, enctype="multipart/form-data", needed to be in the form tag ..
Now it works for me ....