Okay - I'm being blunt here. But I think I have to — to get my point across. When your team works well — it's magic — wonderful — heaven.

Unfortunately, when one or more of your team-members drops the ball spectacularly — it's time for you to diagnose the situation.

There is a spectrum — on one end — LAZY — and on the other — STUPID:

LAZY — They don't care. They don't want to do it. It's below them.
STUPID — They don't know. They are unsure. They are stuck and scared.

Here's the rub — they can be both — They might not know what to do and are too lazy to find out or learn how.

So what do you do?

Diagnose where they are on the spectrum. Most of the time people are not lazy — they just don't know or are afraid of what to do.
Be hard on them to get a clear picture from them where the real OBSTACLE is. Be careful, people are touchy about this.
They need to realize their passivity is impacting you and their progress.
Show them that they need to step up, move from Stupid to Knowledgable, and get stuff done.

In the end, most people move from lack of knowledge to lack of effort (stupid to lazy). Rarely are people lazy — they usually lack direction, purpose, acknowledgement, or focus. Once you shine a light on their inactivity and show them where they need to go, they will start their engines and race to the finish line.