Estou tentando configurar o projeto Maven, JSF e Primefaces. Mas quando eu executo o projeto eu recebo o seguinte erro

com.sun.faces.config.ConfigurationException: 
Source Document: jar:file:/D:/Personal%20Work/eclipse%2032%20Bit/workspace/Java%20EE
/Spring/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps
/ch18_SpringWebFlowAndJSF/WEB-INF/lib/primefaces-3.5.jar!/META-INF/faces-config.xml
Cause: Class 'org.primefaces.component.fileupload.FileUploadRenderer' is missing
 a runtime dependency: java.lang.NoClassDefFoundError: org/apache/commons/fileupload
/FileItem

Aqui está o meu snippet POM

<properties>
    <java-version>1.6</java-version>
    <org.springframework-version>3.2.3.RELEASE</org.springframework-version>
    <org.aspectj-version>1.6.10</org.aspectj-version>
    <org.slf4j-version>1.7.5</org.slf4j-version>
    <jsf-version>2.2.0</jsf-version>
</properties>

    <dependency>
        <groupId>org.springframework.webflow</groupId>
        <artifactId>spring-faces</artifactId>
        <version>2.3.2.RELEASE</version>
    </dependency>

    <dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-api</artifactId>
        <version>${jsf-version}</version>
    </dependency>

    <dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-impl</artifactId>
        <version>${jsf-version}</version>
    </dependency>

    <dependency>
        <groupId>org.primefaces</groupId>
        <artifactId>primefaces</artifactId>
        <version>3.5</version>
    </dependency>
</dependencies>

<repositories>
    <repository>  
        <id>prime-repo</id>  
        <name>PrimeFaces Maven Repository</name>  
        <url>http://repository.primefaces.org</url>  
        <layout>default</layout>  
    </repository>     
</repositories> 

Por que estou recebendo esse erro?

obrigado