Today, when a qassam comes down without doing any damage, hardly anybody will take notice. Next, when a qassam comes down without doing any damage, but succeeding to evade Israeli defences, it is a PR victory for Hamas. Therefore the IDF is reluctant to deploy Iron Dome. It's the fear of failure.
Ya'alon okays administrative detention of Jewish extremist suspected in church arson (Haaretz)
from the article: Gaza border towns demand full state funding of anti-rocket system