Automation - volume is not written

An then all of a sudden, pro tools doesn't write volume automation anymore... I Have Pro Tools 11 and a US-2400 on a macbook pro 8,2. I have been working on this project for days now, only had minor problems with the HUI. Now it doesn't want to write volume automation anymore. Pan e,g, does still work - strange... I deleted the prefs, checked the automation-enabled settings. Every track is on touch... Nothing :-s