acts_as_solr plugin not working properly in rails postgresql


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
I followed the instruction on site URL below:

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 Method)
        at java.lang.ClassLoader.loadClass(
        at sun.misc.Launcher$AppClassLoader.loadClass(
        at java.lang.ClassLoader.loadClass(
        at java.lang.ClassLoader.loadClassInternal(
Could not find the main class: RadRails. Program will exit.

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