hi,i have a problem about veloctiy toolbox.xml in spring mvc

my code:

<bean id="velocityViewResolver"
class="org.springframework.web.servlet.view.veloci ty.VelocityViewResolver">

<property name="toolboxConfigLocation">
<value>/WEB-INF/config/tools.xml</value>
</property>
<property name="dateToolAttribute">
<value>dateTool</value>
</property>
<property name="numberToolAttribute">
<value>numberTool</value>
</property>
...
</bean>

tools.xml

<tools>
<data key="author">Nathan Bubna</data>
<toolbox scope="application">
<tool key="mathTool" class="org.apache.velocity.tools.generic.MathTool"/>
</toolbox>
</tools>

i start my project ,have no problem. but when i use $author,it can't resolve,
please help!