How to set a converter default property?

[[EMAIL PROTECTED]]

Hi, i try to set a default property for a converter in this way:
<validator>
   <validator-id>xyValidtor</validator-name>
   <validator-class>com.xy.XyValidator</validator-class>
   <property>
      <property-name>length</property-name>
      <property-class>java.lang.Integer</property>
      <default-value>40</default-value>
   </property>
</validator>
I expected that setter-Methode of my Member length in the 
XyValidator-Class will called, but only the
default Constructor is called, so why fails my setting of a 
Default-Property?

Can someone help me please!?

-Jörg