I uploaded the K2 v2.6.7 zip file to my test site using normal joomla extension install procedure. I got a "successfull installation " message, and K2 appears in the components list in the roll down menu item of my backend..

However, when I try to access k2 admin panel, I get an error message :"K2HelperHTML not found in administrator/components/com_k2/k2.php on line 77

I run Joomla! 2.5.16, and Iuse Akeeba backup, with its "modified" install script..

What next ?

Complement : I logged out and in again of my backend. I now see a k2 control panel in replacement of the normal Joomla! panel. So maybe everything is well after all?

regards, Paul

Probably something temporary occurred. Let us know if you get the error again. :)