Editing envelope control points - how to remove them?

I am using Ardour (0.99 on Ubuntu 6.06 LTS – yes, yes I know this is ancient … by early June I’m upgrading to Hardy and Ardour 2.30, but I have a project I NEED to finish.) I’m new to Ardour but have been editing the “gain” envelopes by just clicking to add a control point and … I thought … then to remove a point pressing shift and clicking on the control point. (At least this is in the notes I made for myself a month ago when I starting testing Ardour and what I recall doing.) Bottom line: It no longer works. I cannot seem to remove control points once I add them. Is there something obvious I’m missing here … like being in “gain” instead of “object” or vise versa. (I’ve tried 'em all!) Any advice … other than UPGRADE!" … would be appreciated. (BTW: I’m sold on Ardour and cannot wait to get the new one up and running and to donate …)

Try shift and right click