Preview for create/edit content doesn't work

I'm configuring a DRUPAL site web (that it was previously开发者_C百科 created) and I'm testing the diferent options.

When I create a new content or edit a old content and change anything and then I click on 'Preview' doesn't appear the recent changes (just appear the old values), I have to save it before.

NOTE: I do the accions as ROOT (it not a privilege problem).

Anyone knows what is happened?

I think , after you changed any content then you are only clicking preview. [i am assuming]
you don't click on the save button.
if you have clicked on saved also and then also its not coming on recent changes then there will be problem in drupal.
and clear all the caches from browser and also on drupal site.