KML layer problem

Heloo,
I am having a broblem with kml layer. I have created a new kml layer and i defind the URL. The kml file is in my server. When i try to display the map i get "Error during map rendering: TypeError: $.extend is not a function" error. Am i missing something? The URL i use is the absolute URL of the kml file (http://www.mysite.com//sites/all/kml/something.kml)