vishwas I have taken a look at the site and the reason why the native ad placeholder isn't showing is because the native ad placeholder isn't correctly set up. There is limited space to add in a native ad placeholder currently, please can you add in additional content to the side bar and when you have done this please let us know and we can then add a native ad placeholder in there?
When I was looking at your site i noticed that you have made part of the current side bar 'sticky' please can you remove this as it is causing an adsense violation with ads overlapping the side bar. If you would like to use a sticky side bar function for ads we recommend setting up a sticky side bar ad placeholder or 'floating ad placeholder' as an alternative to this.
many thanks