Unable to launch an applet using MZ / FF

Tested OS : windows
Tested bundle :6U4 PIT2 (http://j2se.east/plugin/1.6.0_04-nightly/2007-08-02)

Steps to reproduce:
1. install 6u4 pit2 kernel jre bundle
2. launch mozilla / firefox
3. launch any applet (with object tag) from http://java.sun.com/products/plugin/1.5.0/demos/plugin/applets.html
Applet is not getting launched though the dlls npjpi160_04.dll and npoji610.dll are available under jre6/bin. There was no download / install dialog
Applet is getting launched only after all npjava*.dll are downloaded

Note :
In IE, the applets are working fine.
In MZ and FF, the applets with applet tag are working fine.

Image file attached