asterisk users - Jun 2004 - Queueing and parked calls

I can't park a call that comes from a queue. The situation is:
1. A call gets into a queue.
2. It is answered by an agent.
3. An agent wants to transfer that call to another agent by parking the 
call, but when I dial 700 (to park the call) it hungs up and the call 
isn't parked.
What would be?.