If you want to add any extra modules to apache in custombuild, they'll need to be compiled in. Any module that needs to be compiled in will have a --with-module type flag which will need to be used. To add this flag, run the following:
cd /usr/local/directadmin/custombuild
mkdir -p custom/ap2
cp configure/ap2/configure.apache custom/ap2/configure.apache
vi custom/ap2/configure.apache
# and make sure the  character exists at the end of all lines except the last one.
./build cleanÂ
./build apache
Then restart apache:
RedHat:
/sbin/service httpd restart
FreeBSD:
/usr/local/etc/rc.d/httpd restart
Debian:
/etc/init.d/httpd restart
If you run into problems, you may also need to recompile php as well:
./build php
Then restart apache again.