Configure Tomcat's JVM to pickup JASS config file issue

[H Paul]

(Background: I have an example to run and learn from.)

1. Open a new Dos window and type startup
\apache-tomcat-5.5.33\bin>startup
Another new dos window poped up showing Tomcat is up

Issue
2. A new Dos window and set JAVA_OPTS

\apache-tomcat-5.5.33\bin>set JAVA_OPTS=%JAVA_OPTS% -Djava.security.auth.login.config=C:/example3-jaas.conf

\apache-tomcat-5.5.33\bin>startup

Nothing happened (No new dos window poped up and Tomcat is not up)

1M Thanks.

[H Paul]

1. I just used: set JAVA_OPTS= -Djava.security.auth.login.config=C:/example3-jaas.conf
And a new second window poped up and Tomcat is up.

2. Why with set JAVA_OPTS=%JAVA_OPTS% -Djava.security.auth.login.config=C:/example3-jaas.conf
And a new second window IS NOT poped up and Tomcat is IS NOT up.
Syntax-wise, what is wrong?