Installing OTA App Unable to download

Question

I have an enterprise app that I want to host on my server running IIS 6.0. So I have followed this guide:

http://help.apple.com/iosdeployment-apps/mac/1.1/#app43ad871e

When I click the link to download the app I get the 'Unable to download application' error after the icon started to animate some progress.

• I know that the manifest.plist is found and read because the icon and app-name is loaded OK before the error message.
• I tried changing the MIME types to ".ipa : application/octet-stream" and ".plist : application/x-plist"
• I can browse to and download the .png's and the .ipa-file from the same device Im trying to install it to.
• .ipa and bundle id should be fine as they are hosted on another server without any problems (that I have nothing to do with, but have tried to install the app from there and it works fine).
• I read lots of threads on this but can't seem to identify what is wrong in my scenario.

Here is my manifest file as of now:

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
   <!-- array of downloads. -->
   <key>items</key>
   <array>
       <dict>
           <!-- an array of assets to download -->
           <key>assets</key>
           <array>
               <!-- software-package: the ipa to install. -->
               <dict>
                   <!-- required. the asset kind. -->
                   <key>kind</key>
                   <string>software-package</string>
                   <!-- optional. md5 every n bytes. will restart a chunk if md5 fails. -->
                   <key>md5-size</key>
                   <integer>10485760</integer>
                   <!-- optional. array of md5 hashes for each "md5-size" sized chunk. -->
                   <key>md5s</key>
                   <array>
                       <string>41fa64bb7a7cae5a46bfb45821ac8bba</string>
                       <string>51fa64bb7a7cae5a46bfb45821ac8bba</string>
                   </array>
                   <!-- required. the URL of the file to download. -->
                   <key>url</key>
                   <string>https://app.xxxx.com/site/appName.ipa</string>
               </dict>
               <!-- display-image: the icon to display during download .-->
               <dict>
                   <key>kind</key>
                   <string>display-image</string>
                   <!-- optional. indicates if icon needs shine effect applied. -->
                   <key>needs-shine</key>
                   <true/>
                   <key>url</key>
                   <string>https://app.xxxx.com/site/img57x57.png</string>
               </dict>
               <!-- full-size-image: the large 512x512 icon used by iTunes. -->
               <dict>
                   <key>kind</key>
                   <string>full-size-image</string>
                   <!-- optional. one md5 hash for the entire file. -->
                   <key>md5</key>
                   <string>61fa64bb7a7cae5a46bfb45821ac8bba</string>
                   <key>needs-shine</key>
                   <true/>
                   <key>url</key><string>https://app.xxxx.com/site/img512x512.png</string>
               </dict>
           </array><key>metadata</key>
           <dict>
               <!-- required -->
               <key>bundle-identifier</key>
               <string>my.bundle.id</string>
               <!-- optional (software only) -->
               <key>bundle-version</key>
               <string>1.0.9</string>
               <!-- required. the download kind. -->
               <key>kind</key>
               <string>software</string>
               <!-- optional. displayed during download; typically company name -->
               <key>subtitle</key>
               <string>Me</string>
               <!-- required. the title to display during the download. -->
               <key>title</key>
               <string>My App Name</string>
           </dict>
       </dict>
   </array>
</dict>
</plist>

And the link to install the app:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Sample iOS OTA install</title>

</head>

<body>

<a href="itms-services://?action=download-manifest&url=https://app.xxxx.com/site/manifest.plist">Install App</a>
</body>
</html>