Roadblocks associated with building a team

Recently a colleague reminded me of a discussion I started twelve years ago on the roadblocks associated with leadership. I felt the discussion was quite spirited and educational for us all. The question was: "What do you feel is the most significant roadblock to building a team, any team. From an engine company, station crew or battalion to a special operations team such as hazardous materials or technical rescue?"

Being the lifelong learners we are, I am curious how the answers change, or remain the same over time. I know our perspective has changed quite a bit since I originally posted this discussion.

What are your thoughts on this subject?