How to increase PR of my inner pages ?

If you have a blog make sure you update it at least once a week. Start submitting your inner pages to high authoritative directories, write engaging articles, submit to social bookmarking sites, etc. Page rank is not that important in my opinion, but to increase it you might want to reconsider your on page seo strategy.

PR doesn't matter, traffic matters. push your pages to get the traffic from search engines. ultimately you will get the PR al last. don't worry and be happy

Sure, better change your point of attention to target traffic.
PR of inner links depends on inner linking structure.

Adjust your inner linking.
Keep in mind very important role of quality traffic.
Use google analytics to check sessions (they may give you some tips).

Some reasons why PR still 0 for inner pages:
- inner linking management fails,
- missing strategy of external linking(direct targeting to homepage),
- trust and popularity at low range.

If you want to increase the page rank of your inner page then you can do Off page SEo for these pages same as that of your home page. This will also create back link for your inner pages and helps you to increase your pr for your inner pages.