Forbidden while changing tracking only

Hi.
I’m trying to use this plugin with a fresh-install of wordpress and everything seens to be ok, except that I can’t save tracking settings.
I’ve checked file/folder permissions and looks ok. It’s a fresh install withoyt any plugins, except this google plugin. All settings works fine when I change and save……just don’t work when I change anything in Tracking menu, I got an Forbidden error. Any tips/idea?