NDBCLUSTER engine not exists (no replies)

Hi
I'm trying to setup a cluster on ubuntu server, after submit "ALTER TABLE mytable ENGINE=NDBCLUSTER;", I find nothing changed, my table is still using InnoDB.
And There's no "NDBCLUSTER" in show engines.
I've install both mysql-server(5.5) and Cluster release(deb).
How can I add this engine?
Please help, thank you!