Radical - A lightweight Java RAD tool

hi i installed radical but when i tried to run that i got the following
exception

Radical: Could not load palette.
Radical: java.io.InvalidClassException:
javax.swing.ImageIcon$AccessibleImageIcon; local class incompatible: stream
classdesc serialVersionUID = -3994512798706967451, local class
serialVersionUID = -1903458698681874148
Exception in thread "main" java.lang.NullPointerException
at org.ungoverned.radical.Radical.<init>(Radical.java:253)
at org.ungoverned.radical.Radical.createRadical(Radical.java:149)
at org.ungoverned.radical.Radical.main(Radical.java:1820)