Freepbx and fax

i have a problem to receive fax.
i have asterisk 1.4.11 and freepbx
When the system receive a fax from analog line, the system recognize the fax tone and send the call to the fax extension.
The fax machine answer the call and try to receive the fax but when the trasmission have finished, asterisk hangup the extension and try to send one email with the fax.
I have selected, in general setting, the right extension and i dont want to use asterisk to receive faxes.
In 1.2 version of asterisk i dont have this problem. this is a bug or mismatch configuration?
i’m sorry for my poor english.
thanks for help