strict standards - variables issue

fionacampbell

My website http://rubyslippersphoto.com/ is reading the following in all albums...

Strict Standards: Only variables should be assigned by reference in /data01/rubys/public_html/zp-core/classes.php on line 233

I've cleared up the public folder and have no idea what this means. can anyone help?
Many thanks

fretzl

You're running a really old version of Zenphoto.
Please try upgrading.