Call recording problem

Hi all!

Here is the part of custom_extension.conf:
same => n,Playback(custom/state_your_name)
same => n,Record(XY.wav,2,60)
same => n,Playback(custom/thank_you)

The problem:
When I’m speaking in the phone until 2-10 second, the recording accidentally finish.
What’s the problem?

When I’m speaking quietly in the phone, the record stop after 2s.
How to increase the record volume?