[Plugin: Infinite-Scroll] Can not activate plugin – redirected to home page

I want so much this infinite scroll. But there is problem when I am trying to activate plug in.

I am using Thesis theme and when i press activate, I am redirected to home page.

Same happens when I want to delete plug in…

Can anyone explain what and why is happening?

http://wordpress.org/extend/plugins/infinite-scroll/

[ Please do not bump, it’s not permitted here. If it’s really urgent then consider hiring someone. ]