log4j:ERROR Could not create a custom Appender whe

Question

I am having below tag in my log4j.xml

<appender name="TEST_APPENDER" class="com.test.TESTAppender">
  <layout class="org.apache.log4j.SimpleLayout" />
</appender>

for it I am using below jars

apache-log4j-extras.jar
log4j.jar

and when I am deploying war file in tomcat, it is giving below exception

log4j:ERROR Could not create an Appender. Reported error follows.
java.lang.ClassNotFoundException: com.test.TESTAppender
        at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:191)
        at org.apache.log4j.helpers.Loader.loadClass(Loader.java:198)
        at org.apache.log4j.xml.DOMConfigurator.parseAppender(DOMConfigurator.java:247)
        at org.apache.log4j.xml.DOMConfigurator.findAppenderByName(DOMConfigurator.java:176)
        at org.apache.log4j.xml.DOMConfigurator.findAppenderByReference(DOMConfigurator.java:191)
        at org.apache.log4j.xml.DOMConfigurator.parseAppender(DOMConfigurator.java:284)
        at org.apache.log4j.xml.DOMConfigurator.findAppenderByName(DOMConfigurator.java:176)
        at org.apache.log4j.xml.DOMConfigurator.findAppenderByReference(DOMConfigurator.java:191)
        at org.apache.log4j.xml.DOMConfigurator.parseChildrenOfLoggerElement(DOMConfigurator.java:523)
        at org.apache.log4j.xml.DOMConfigurator.parseCategory(DOMConfigurator.java:436)
        at org.apache.log4j.xml.DOMConfigurator.parse(DOMConfigurator.java:1004)
        at org.apache.log4j.xml.DOMConfigurator.doConfigure(DOMConfigurator.java:872)
        at org.apache.log4j.xml.DOMConfigurator.doConfigure(DOMConfigurator.java:778)
        at org.apache.log4j.helpers.OptionConverter.selectAndConfigure(OptionConverter.java:526)
        at org.apache.log4j.LogManager.<clinit>(LogManager.java:127)
        at org.apache.log4j.Logger.getLogger(Logger.java:104)
        at org.apache.commons.logging.impl.Log4JLogger.getLogger(Log4JLogger.java:289)
        at org.apache.commons.logging.impl.Log4JLogger.<init>(Log4JLogger.java:109)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at org.apache.commons.logging.impl.LogFactoryImpl.createLogFromClass(LogFactoryImpl.java:1116)
        at org.apache.commons.logging.impl.LogFactoryImpl.discoverLogImplementation(LogFactoryImpl.java:914)
        at org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.java:604)
        at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:336)
        at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:310)
        at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:685)
        at org.springframework.web.context.ContextLoader.<clinit>(ContextLoader.java:146)
        at org.springframework.web.context.ContextLoaderListener.createContextLoader(ContextLoaderListener.java:53)
        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:44)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5016)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5528)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)

but class TESTAppender is available at this path /WEB-INF/classes/com/test/ I am not able to understand why this exception is coming

please suggest.