acts_as_solr plugin not working properly in rails postgresql

Hi,

I have implement books search application in ruby on rails with solr
server search.

I am using rails 2.3.2 , postgresql-8.3.11 in CentOS and acts_as_solr
plugin.
I followed the instruction on site URL below:
http://www.lucidimagination.com/blog/2009/02/17/acts_as_solr_cell/

When I run rake solr:start I am getting error as

Exception in thread "main" java.lang.NoClassDefFoundError: RadRails
Caused by: java.lang.ClassNotFoundException: RadRails
        at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:319)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:264)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:332)
Could not find the main class: RadRails. Program will exit.

Kindly help me to solve and run the simple application using apache
solr.
Thanx in advance.