Arduino on Linux

hi i was following the installation instruction on the post above without any trouble but as soon as i do ./run.sh i get this error:
olsen@ll-928:~/lab/arduino/trunk/build/linux$ ./run.sh
Exception in thread "main" java.lang.NoClassDefFoundError: processing.app.Base
at gnu.java.lang.MainThread.run(libgcj.so.7)
Caused by: java.lang.ClassNotFoundException: processing.app.Base not found in gnu.gcj.runtime.SystemClassLoader{urls=[file:lib/,file:lib/build/,file:lib/pde.jar,file:lib/antlr.jar,file:lib/oro.jar,file:lib/registry.jar,file:lib/mrj.jar,file:lib/RXTXcomm.jar], parent=gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}}
at java.net.URLClassLoader.findClass(libgcj.so.7)
at java.lang.ClassLoader.loadClass(libgcj.so.7)
at java.lang.ClassLoader.loadClass(libgcj.so.7)
at java.lang.Class.forName(libgcj.so.7)
at gnu.java.lang.MainThread.run(libgcj.so.7)
...
any clue around?
thanks&greets
olsen