Problems installing GeoGebra

[stan]

I want to try to use GeoGebra to teach a young person math. I downloaded
the installer, but when I run it it says it needs Jave > 1.4 But I have the
following installed:

sun-java6-jre is already the newest version.
sun-java6-jre set to manual installed.

What can I do to fix this problem?

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