Java web start - Unable to load resource

I've got a jar that loads great with java web start when I browse through the IP address of the server. Once I try the server name instead I get the following exception:

com.sun.deploy.net.FailedDownloadException: Unable to load resource:
    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.javaws.LaunchDownload$DownloadTask.call(Unknown Source)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

The wrapped exception:

java.io.FileNotFoundException: 
  at sun.reflect.GeneratedConstructorAccessor2.newInstance(Unknown Source)
  at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
  at java.lang.reflect.Constructor.newInstance(Unknown Source)
  at sun.net.www.protocol.http.HttpURLConnection$6.run(Unknown Source)
  at java.security.AccessController.doPrivileged(Native Method)
  at sun.net.www.protocol.http.HttpURLConnection.getChainedException(Unknown Source)
  at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
  at com.sun.deploy.net.BasicHttpRequest.doRequest(Unknown Source)
  at com.sun.deploy.net.BasicHttpRequest.doRequest(Unknown Source)
  at com.sun.deploy.net.BasicHttpRequest.doGetRequest(Unknown Source)
  at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source)
  at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
  at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
  at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
  at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
  at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
  at com.sun.javaws.LaunchDownload$DownloadTask.call(Unknown Source)
  at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
  at java.util.concurrent.FutureTask.run(Unknown Source)
  at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
  at java.lang.Thread.run(Unknown Source)
Caused by: java.io.FileNotFoundException: 
  at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
  at java.net.HttpURLConnection.getResponseCode(Unknown Source)
  ... 15 more

JNLP:

<?xml version="1.0" encoding="utf-8"?>
<jnlp
    spec="1.0+"
    codebase="http://servername/Site/Views/.."
    href="">
    <information>
        <title>title</title>
        <vendor>vendor</vendor>
        <description>description</description>
        <description kind="short">short</description>
        <icon href="../../icon.gif" />
    </information>
    <security>
        <all-permissions/>
    </security>
    <resources>

        <j2se version="1.5+" java-vm-args="-Xmx1000M -Xms150M" initial-heap-size="150M" max-heap-size="1000M" />
        <j2se version="1.4.2+" href="http://java.sun.com/products/autodl/j2se" java-vm-args="-Xmx1000M -Xms150M" initial-heap-size="150M" max-heap-size="1000M" />

        <jar href="/file.jar"/>
    </resources>
    <application-desc main-class="com....">
        <argument>CD6B172DEC34924D83EA64A61A6550BE1271325929392</argument>
        <argument>http://servername/file.asp</argument>
        <argument>/Site</argument>
    </application-desc>
</jnlp>

Any idea what should I look for?

I've changed the java proxy settings to direct connection - and it works.