Missing action error not being caught

I keep getting a blank page containing only the following:

"There was a controller specfic error processing your request."

Though I have the following in my application.rb

def rescue_action_in_public(exception)
        case exception
        when UnknownAction, ActiveRecord::RecordNotFound then
            render :controller => "application", :action =>
"error_404", :status => 404
        else
            render :text => "errors/unhandled", :status => 505
        end
    end

Well. A lot has happened since this error. It is gone now, but I am not
sure what fixed it.

I think it was changing "UnknownAction" to
"::ActionController::UnknownAction"

-Matt