Cannot Start Ambari Server on the box

Hello Everyone, can someone help … download the sandbox 2.3. I was able to start Amabari Agent but not the Amabari server on the sandbox. It comes up with error.
[root@sandbox ~]# ambari-server start
Using python /usr/bin/python2.6
Starting ambari-server
Ambari Server running with administrator privileges.
Running initdb: This may take upto a minute.
About to start PostgreSQL
ERROR: Exiting with exit code 3.
REASON: Unable to start PostgreSQL server. Status stopped. . Exiting
[root@sandbox ~]#
[root@sandbox ~]# ambari-agent start
Verifying Python version compatibility…
Using python /usr/bin/python2.6
Checking for previously running Ambari Agent…
Starting ambari-agent
Verifying ambari-agent process status…
Ambari Agent successfully started