[Solved] Automation Write enable/disable

This is a little embarrassing but I can't seem to find my answer in the reference guide (although I'm sure it's there).
So I have a bunch of tracks with volume envelopes that I suddenly can't edit...I feel sure I toggled something with my keyboard but what?
When I click on the envelope to add a node the "clear all automation enable" on the control bar lights up.
So I go to the track and toggle the "automation write" button but still can't add a node.
What the heck did I do?
Thanks very much,
Randy
EDIT- in fact none of the existing envelopes are working
EDIT 2- I just looked in the shortcut list and apparently I had inadvertently hit F12 ...all is well : )