Launch File Error in Java Web Start

I'm trying to launch a java app via web start and I'm getting the following error which I can't seem to figure out. Any hints, tips or tricks to resolve this would be greatly appreciated.

JNLPException[category: Launch File Error : Exception: null : LaunchDesc: 
<jnlp spec="1.0+" codebase="http://javadl.sun.com/webapps/jawsautodl/AutoDL/j2se/">
  <information>
    <title>J2R开发者_开发问答E 1.5.0_22 Installer</title>
    <vendor>Sun Microsystems, Inc.</vendor>
    <homepage href="null"/>
  </information>
  <security>
    <all-permissions/>
  </security>
  <update check="timeout" policy="always"/>
  <resources>
    <java href="http://java.sun.com/products/autodl/j2se" version="1.3+"/>
    <jar href="http://javadl.sun.com/webapps/jawsautodl/AutoDL/j2se/javaws-j2re-inst.jar" download="eager" main="false"/>
    <property name="installerLocation" value="jre-1_5_0_22-linux-i586.bin"/>
    <property name="installerSize" value="17283082"/>
    <property name="javaVersion" value="1.5.0_22"/>
    <property name="platformVersion" value="1.5"/>
    <property name="licenseSize" value="13238"/>
    <property name="waitString.0" value="[yes or no]"/>
    <property name="responseString.0" value="yes"/>
    <property name="osplatform" value="linux-i586"/>
  </resources>
  <installer-desc main-class="com.sun.webstart.installers.Main"/>
</jnlp> ]
    at com.sun.javaws.JnlpxArgs.executeInstallers(JnlpxArgs.java:500)
at com.sun.javaws.Launcher.prepareResources(Launcher.java:993)
at com.sun.javaws.Launcher.prepareAllResources(Launcher.java:621)
at com.sun.javaws.Launcher.prepareToLaunch(Launcher.java:327)
at com.sun.javaws.Launcher.prepareToLaunch(Launcher.java:199)
at com.sun.javaws.Launcher.launch(Launcher.java:116)
at com.sun.javaws.Main.launchApp(Main.java:417)
at com.sun.javaws.Main.continueInSecureThread(Main.java:249)
at com.sun.javaws.Main$1.run(Main.java:111)
at java.lang.Thread.run(Thread.java:662)

When "Web Start" run the installer-desc class, needs to know the result of the installer. If it don't get answer then the exception appears.

Communicate with "Web Start" in this way:

ExtensionInstallerService installerService =
            (ExtensionInstallerService) ServiceManager.
                lookup("javax.jnlp.ExtensionInstallerService");

//Say Successfully
installerService.installSucceeded(false);

//Say failure
installerService.installFailed();

I notice you have

<homepage href="null"/>

That seems like it could be the source of your problem? If you don't have a homepage, you might try omitting that tag, instead of setting a null value.