How do I make this spring class not found error go away?

Will someone please explain why I'm getting this build error, when the class is obviously there. Here's the error -

org.springframework.beans.factory.BeanDefinitionStoreException: Une开发者_如何学Cxpected exception parsing XML document from ServletContext resource [/WEB-INF/spring-servlet.xml]; nested exception is java.lang.NoClassDefFoundError: org/springframework/aop/scope/ScopedProxyUtils

and here's my spring-servlet.xml file -

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
<context:annotation-config />
<context:component-scan
    base-package="com.website" />
<bean id="viewResolver"
    class="org.springframework.web.servlet.view.UrlBasedViewResolver">
    <property name="viewClass"
        value="org.springframework.web.servlet.view.JstlView" />
    <property name="prefix" value="/WEB-INF/views/" />
    <property name="suffix" value=".jsp" />
</bean>

<bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
    <property name="basenames">
        <value>/WEB-INF/messages/messages</value>
    </property>
    <property name="cacheSeconds" value="60" />
    <property name="defaultEncoding" value="UTF-8" />
</bean>
</beans>

I also have the aop jar on my classpath-

<classpathentry kind="lib" path="WebContent/WEB-INF/lib/org.springframework.aop-sources-3.0.5.RELEASE.jar"/>

That is the sources jar...

path="WebContent/WEB-INF/lib/org.springframework.aop-sources-3.0.5.RELEASE.jar"

Get the binary release version.