First Rule of Leadership...

EVERYTHING IS YOUR FAULT!!! I know it sounds harsh and it may seem like the jaded rant of a cartoon villain, but it is truth. To be considered a trusted leader to those that work under your guidance, you have to be willing to accept fault that may not technically be yours to take. If you throw them under the bus and point the finger at them every time something goes wrong, pretty soon you will have nobody working for you at all.
I'm not saying that you shouldn't reprimand someone that consistently does wrong or make it clear to the group that better is expected of them in the future. The bottom line is that as their leader you are responsible for them. You get to celebrate their victories knowing that you played a role in helping them to achieve it. On the opposite side of things, you must also share in their failures knowing that you also played a role and most likely could have improved your methods to help keep them from it.
The gist is this: You are a part of a team. You win as a team. You lose as a team. As the leader of that team, you are ultimately responsible for the winning and for the losing.
When you take a hit from your boss (because we all answer to someone) for mistakes made by a member or members of your team, you assure them that you are worthy of their trust. People will work hard and with a strong sense of loyalty and dedication for leaders they know they can trust.