1. If you are getting the "java.security.AccessControlException", you must sign the applet before using it in a browser. See the "How to sign Java applet" tutorial for details.

2. If you are getting "java.lang.NullPointerException at sun.plugin2.applet.Plugin2Manager.findAppletJDKLevel (Unknown Source)", this means that the Java VM cannot find some of the dependent classes ("Class-Path" problem).

For an applet which uses Active Query Builder Java Edition, you must specify a reference to the ActiveQueryBuilder.jar in the jar file's manifest. For example:

Class-Path: lib/ActiveQueryBuilder.jar

Also, you can specify it in the "archive" attribute of the <applet> tag:

<APPLET code="appletdemo/QueryBuilderApplet.class" archive="AppletDemo.jar,ActiveQueryBuilder.jar" width=800 height=600></APPLET>