Angular JS with facebook sharing

URL not redirecting to Prerender.io when sharing the url from facebook.

My site is http://www.vbuy.in/ , which is in demo and I am trying to share one of the url in facebook for example "http://www.vbuy.in/product/samsung-galaxy-grand-2-black-/1975"

1. Title and Description are showing from the home page (I added all those supported ng-content, and in script i registed the viewtitle etc..

2. I wrote a URL rewrite and also tested in https://developers.facebook.com/tools/debug/og/object/.

But, for me it looks like its not redirecting to prerender.io url. What Am I missing here? . I use IIS and also downloaded ARR and enabled proxy there.

I am having tough times for the last one week with SEO & social sharing part. Even before starting the project we were aware of SEO issues in angular js, but we thought when we go live, we can use prerender or any pre render static html support. ( we didnt evaluated in depth earlier, due to time & resource constraints)

My code .. (Which is copied from other Stack overflow solutions.

<httpProtocol>
  <customHeaders>
    <add name="X-Prerender-Token" value="XXXXX....." />
  </customHeaders>
</httpProtocol>

<rewrite>
  <rules>

    <rule name="Prerender" stopProcessing="true">
      <match url="^(?!.*?(\.js|\.css|\.xml|\.less|\.png|\.jpg|\.jpeg|\.gif|\.pdf|\.doc|\.txt|\.ico|\.rss|\.zip|\.mp3|\.rar|\.exe|\.wmv|\.doc|\.avi|\.ppt|\.mpg|\.mpeg|\.tif|\.wav|\.mov|\.psd|\.ai|\.xls|\.mp4|\.m4a|\.swf|\.dat|\.dmg|\.iso|\.flv|\.m4v|\.torrent))(.*)" ignoreCase="false" />
      <conditions logicalGrouping="MatchAny">
        <add input="{HTTP_USER_AGENT}" pattern="googlebot|baiduspider|facebookexternalhit|twitterbot" />
        <add input="{QUERY_STRING}" pattern="_escaped_fragment_" ignoreCase="false" />
      </conditions>
      <action type="Rewrite" url="http://service.prerender.io/http://www.vbuy.in/{R:1}" />
    </rule>