PHP Fatal error: Class 'Memcache' not found

[hce]

Hi,

I installed lighttpd, php and memcached in FC6, and I have run the
script to start memcached:

nobody    6775  0.0  0.0  32848   816 ?        Ssl  11:26   0:00
memcached -d -p 11211 -u nobody -m 64 -c 1024 -P
/var/run/memcached/memcached.pid

But the php could not find the "extends Memcache" in an php file:

2008-04-09 12:21:45: (mod_fastcgi.c.2592) FastCGI-stderr: PHP Fatal
error:  Class 'Memcache' not found

What I was missing?

Thank you.

Jim