I am using User Points and Rules. Users earn points for publishing and commenting but are deducted points for flagging their articles for announcement on the front page (a kind of a fee). The fee per announcement is say 150 points.

Obviously, if they don't have at least 150 points, they should not be able to flag. So I need a rule that would check if the author has at least 150 points and if not - block the flagging action with an error message: Sorry, you don't have enough.

Yet, I just can't figure out how to set up such a rule. Any help would be highly appreciated.