Directadmin install memcached using percl problems.
cd /usr/local/src
wget https://launchpad.net/libmemcached/1.0/1.0.15/+download/libmemcached-1.0.15.tar.gz
tar -zxvf libmemcached-1.0.15.tar.gz
cd libmemcached-1.0.15
./configure
make
make install