Why my website landing page is not caching?

[Aaditya]

I have a landing page http://www.example.com/ caching date, but now I want that my landing page should be cached also.

[Gaius]

add a Google plus 1 to the page and wait 2-3 days

[James]

try to do link building of inner page of your inner page.
some of techniques such as:
submitting to high pr bookmarking site
write an article and gives two hyperlinks one is inner page & other to be done of home page or contact page.

submit to google webmasters tools the inner link.
it will really help you.