FileNotFountException when I re-deploy my web app,help me!

[yangjs]

I am user jbossAS jboss-4.0.2

In my app, i put one resource file (xyz.properties) in $jboss.server.home.dir/conf! my webapp while load it by thread context classpath,then I deploy my war in $jboss.server.home.dir/deploy,everything is ok,but when I re-deploy this war,I found the $jboss.server.home.dir/conf/xyz.properties can't found and throws FileNotFountException ,I read doc about jboss classload,but can't explain ......who can help me!!

[yangjs]

My tomcat's jboss-service.xml config about classload is :

<attribute name="Java2ClassLoadingCompliance">false</attribute>

 <attribute name="UseJBossWebLoader">true</attribute>

No one can explain it???