Why can't I un-retweet a Tweet?

[mickie]

I want to unretweet some tweets back from September. I see the green "retweet" button at the bottom of the Tweet, but when I click on it to undo it, nothing happens. It doesn't turn gray nor disappears from my Timeline.

Anything else I can do?

Thank you.

(Yes, I know I can't delete the original Tweet; I just want it off my profile).
There is no "delete" button for Retweets .
Spencer - I just tested that too and it works from the retweets I did today; I'm just wondering why they're not working with the ones from September. Like, is there a reason why I can't unretweet old tweets? Thank you though!