SAP EHP Installer not working

Hi

I've installed EHP installer, but when I go in through the web gui <host>4239, I manage to get to the initial page. When clicking on the EHP Installer link, it opens up Java 6 and I then get the following message:

Unable to launch application:

com.sun.deploy.net.FailedDownloadException: Unable to load resource: http://I5SAP:4239/sdtdsu.jnlp

     at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source)

     at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)

     at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)

     at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)

     at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)

     at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)

     at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)

     at com.sun.javaws.Launcher.updateFinalLaunchDesc(Unknown Source)

     at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)

     at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)

     at com.sun.javaws.Launcher.launch(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)

Any ideas?