Prev Next Navigation dont work at 2.5

Hello,

the joomla prev next navigation in the articles dont work. The navigation setting is "show" in the article settings.

Is it a Joomla problem or a template problem? How can i fix. At the 1.7 version all works perfect.

I have overwrite the pagenavigation plugin folder with the old one of Joomla 1.7. Now its working???