Not able to start mysql (no replies)

When i am running mysql.server start i got error
PId file not found

my.cnf configuration is like that
[mysqld]
ndbcluster
ndb-connectstring='host=172.21.109.74'
datadir=/var/lib/mysql
socket=/tmp/mysql.sock
pid-file=/var/run/mysqld/mysqld.pid
#socket=/var/lib/mysql/mysql.sock
user=mysql
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
old_passwords=1

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[mysql_cluster]
ndb-connectstring='host=172.21.109.74'