[Gvsig_english] problem installing sextante

[Wolfgang Qual]

Hi list,
I downloaded the latest stable version of sextante. When trying to install it 
(kunbuntu 7.10, gvsig 1.1.1 installed), the following error message is 
printed:

"wqual at standalone$ java -jar sextante.jar
The application that you are trying to install requires a 1.5 version or later 
of the Java platform.
You are running a 1.4.2-02 version of the Java platform.
Please upgrade to a newer version."

I do not really understand this. gvSIG has it's own java platform - isn't it 
possible for sextante to use the same? Any suggestions?

Best regards && have a nice evening.
Wolfgang