NOM doesn't work after upgrade to 6.5.3 from 6.0mp4.

I upgraded NOM/Client/VxAT to 6.5.3 from 6.0mp4. But NOM doesn't work after the upgrade. 

Everytime when I tried to start VRTSnomSrvr service, I got the following error messages from Event Viewer.

The Java Virtual Machine has exited with a code of 12, the service is being stopped.

And when I try to run the java version, I got the following errors. Anyone can help me sort it out? Thanks in advance.

C:\Program Files\Veritas\NetBackup Operations Manager\db\java>java -version
Error opening registry key 'Software\JavaSoft\Java Runtime Environment'
Error: could not find java.dll
Error: could not find Java 2 Runtime Environment.