#12 make file not working

[Ugo fantozzi]

i'm trying to install appconference but when i launch the make command it's returned an error like this:

In file included from /usr/include/inttypes.h:26,
from /usr/include/asterisk/compat.h:20,
from /usr/include/asterisk/asterisk.h:30,
from app_conference.c:28:
/usr/include/asterisk/features.h:46: error: expected specifier-qualifier-list before ‘AST_LIST_ENTRY’

and the installation fails...
I've tried to change version of asterisk (i've tried 1.4.17 and 1.4.22), with ubuntu-server 8.04 and 7.10...
The path to the include dir is correct but the error still remain....

HELP!!!!
Thanks in advance...