SAP Gui for Java

hi. I have some problem with the above.

After installing all the files on the server, i tried using the demo.htm file came with SAPGUI for java. At the server, the applet on the demo.htm is showing fine, so with a few other users. but there's 1 user that couldn't see the applet. So, we isolated the problem to be the user's computer. we have installed a new JRE plugin and the user could see the sample applet on the sun website. but still, the user couldn't see the applet in demo.htm.

what could be the problem? pls help. thanks.