file did not open after extracting zip created by DotNetZip

What is wrong in my below code?

[HttpPost]
[ValidateAntiForgeryTokenAjax]
public ActionResult Generatezip(List imageList)
{
string imgRootPath = ConfigurationManager.AppSettings["filepath"] + "\\";
string imgFile = string.Empty;
string imgKey = string.Empty;
string fileName = "DaysImage_";
try
{
var ms = new MemoryStream();

if (imageList.Count > 0)
{
string[] fileNames = imageList.FirstOrDefault().ToString().ToLower().Split('\\');
fileName += fileNames[0] + fileNames[1] + fileNames[2] + ".zip";

using (ZipFile zipFile = new ZipFile())
{
foreach (var imgPath in imageList)
{
imgKey = imgPath.Substring(imgPath.LastIndexOf("\\") + 1);
imgFile = imgRootPath + imgPath;
zipFile.AddEntry(imgKey, imgFile);
//zipFile.AddFile(imgFile);
}
zipFile.Save(ms);
TempData[fileName] = ms;
// zipFile.Save(ms);
}
}

ms.Position = 0;
return Json(new { success = true, fileName }, JsonRequestBehavior.AllowGet);
}
catch (Exception ex)
{
Logger.LogError(ex);
return Json(new { success = false, fileName }, JsonRequestBehavior.AllowGet);

}
}

public ActionResult DownloadImageZip(string fileName)
{
var ms = TempData[fileName] as MemoryStream;
if (ms == null)
return new EmptyResult();
TempData[fileName] = null;
return File(ms, "application/zip", fileName);
}
}