[F9 64-bit] jperf Java f/e for iperf - Java exception error

[techmum]

Have iperf installed.

Downloaded JPerf from >
http://code.google.com/p/xjperf/

chmod +x jperf.sh

./jperf.sh

Get following errors:
Exception in thread "main" java.lang.NoClassDefFoundError: org/jdesktop/swingx/JXTaskPaneContainer
at net.nlanr.jperf.JPerf.main(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.jdesktop.swingx.JXTaskPaneContainer
at java.net.URLClassLoader$1.run(URLClassLoader.java: 217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 23)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 68)
at java.lang.ClassLoader.loadClassInternal(ClassLoade r.java:336)
... 1 more

Anyone know what might be the problem?