wsadmin and setting web module classloader to PARENT_LAST

[tt2005]

I'm trying to set the WAR file web module classloader to PARENT_LAST with wsadmin. However, I couldn't figure out why the script below would fail at AdminConfig create WebModuleConfig...
...
I did the same on EAR app classloader level with AdminConfig modify and it works fine. Anyone any idea? The wsadmin doesn't seem to have an indept documents on setting classloader at War file web module level.
----

proc setWARClassloader {} {
global AdminConfig
#
set deployments [$AdminConfig getid /Deployment:$appname/]
set deploymentObject [$AdminConfig showAttribute $deployments deployedObject]
set classloader [$AdminConfig showAttribute $deploymentObject modules ]
set modeattr [list classloaderMode $mode]
set attrs [list $modeattr]
#
$AdminConfig create WebModuleConfig "$classloader" "$attrs"

$AdminConfig save
}

thanks,
tt