Timestamp option of javaws throws NullPointerException

Tested Build : 6u10 b26 PIT
Tested OS : windows

Steps to reproduce :
1. Install jre
2. clear cache
3. try to import the appln with timestamp option

./javaws -import -timestamp "06/09/2008 5:30 PM" http://java.sun.com/products/javawebstart/apps/notepad.jnlp

It throws NullPointerException

java.lang.NullPointerException
   at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
   at com.sun.deploy.net.DownloadEngine.getCachedFile(Unknown Source)
   at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source)
   at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source)
   at com.sun.javaws.Main.launchApp(Unknown Source)
   at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
   at com.sun.javaws.Main$1.run(Unknown Source)
   at java.lang.Thread.run(Unknown Source)

Expected behavior :
There should be no exception and import resources whose lastModified date is later than the timestamp provided.