[Plugin: ?Feed] Gives an error message

I am using this plugin in several sites of mine but on one specific site as soon as I hit update changes to save the settings I get a message that says

“You do not have sufficient permissions to edit plugins for this blog.”

I am getting this error on only one website and it just works great on others..

I am admin on the blog and I am the only user on the blog but I am still getting this error…

Any idea why & how this can be fixed?