The metatag display different result at $page and $node and also don't works

In my production site the metatag dont works at node page, but works at front page.

I use the below code debug it at template.php,

function theme_preprocess_page(&$vars){
  dpm($vars);
}

function theme_preprocess_node(&$vars){
  dpm($vars);
}

In the Production site, the result:

$node
$page

It is really strange

And i also install a new drupal site(7.21) and test
I enable the locale and content translate module like my production site.

The test site works fine. The result is same when i debug $page and $node.

$node
$page

So can someone help me analyse it, what is the problem.

And I also install a previous version metatag, the version is : version = "7.x-1.0-beta1+20-dev"
It works fine at my production site.

I am crazy.Hope someone can help me.

Thanks!