Latest nightly build, default theme.
I changed hitcounter to the new function, like this , and I get this error

Fatal error: Call to a member function get() on a non-object in \Desktop\localhost\htdocs\zpt\zp-core\template-functions.php on line 3012

How can I fix it? Thanks.

You are using it wrong, if you pass anything it needs to be the object of the current image or album. Please review this thread http://www.zenphoto.org/support/topic.php?id=4664#post-27471 and also read the documentation.