Async AGI

i really use AGI and use command ANSWER, but i have the prolem : Message: Failed to add AGI command to channel SIP/101-00000003 queue
to solve this problem i have to set AGI async in dialplan, but i do not know how can set it.
could you help me?

thanks.

Same here. I would like to send AGI command to pickup call, but it says in the CLI that the channel is not setup for Async AGI.