[Plugin: WordPress Menu Creator] My Meny Creator dosn´t work, please help

Hi I was trying to install WP menu creator.
I have put it in plugins
Activated the plugin.
Pasted the id code in the end of my header.php
Im able to create the my menu but when I open it to
create a “new menu item” in the “edit menu” I get problem.
Nothing happends after I click on “create new menu item” The page loads but then it just comes back again without any new item.

What can I do?

Thanks so much!
The plugin seems really cool tho! Please help me make it work.
Thanks
Ruben
Sweden