troubles with error pages

[reno]

hello,

i 've got this exception

java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
     ....
        at java.lang.Thread.run(Thread.java:595)
Caused by: java.lang.NullPointerException
    ....

in my web.xml, i put this xml tags:

<error-page>
        <error-code>404</error-code>
        <location>/serv/ErrorBis</location>
</error-page>

<error-page>
        <exception-type>java.lang.NullPointerException</exception-type>
        <location>/serv/ErrorBis</location>
</error-page>

<error-page>

<exception-type>java.lang.reflect.InvocationTargetException</exception-type>
        <location>/serv/ErrorBis</location>
</error-page>

the exception is not handling for this exception. it works well for a
404 exception but not for a nullPointer...

could you tell me why?

regards
Fred