I came across this after accidentally setting the wrong date for a time restricted activity that was setup a few weeks in advance. I had intended the activity to be available for a few days but accidentally set the month to the current one when I was specifying Steps to recreate:
Setup an activity/label/file
Add a date restriction (from) 11th November 2014 (today)
Add a date restriction (until) 14th October 2014 (last month)
Save.

Result - the activity never becomes available.

Expected result - Moodle should not allow you to save the activity if the dates are in conflict, as it does when setting Timing for activities such as quizzes. If you have both from and until dates, the until date should be in the future now and when when compared to the from date.

Regards, Gordon.