If you do not see either a green button or a red square, Java is not enabled.
Enabling Java in Internet Explorer.
Enabling Java in Netscape Navigator.
If you see the red square, but not the green button, you have an old version of Java.
Click this link to download and install the plug-in for the latest version of Java.
It may help if you download the latest version of the browser (Internet Explorer, Netscape, etc.)