com.sun.deploy.net.jarsigningexception could not verify signing in resource: xalan.jar, 2.7.1

Our JNLP client application contains different JAR's. We sign all these JAR's at build-process. Now, we have one Jar which can not be verified, but only under Windows! (xalan-2.7.1.jar)

If we run the JNLP under windows, we get this exception:

com.sun.deploy.net.JARSigningException: could not verify signing in resource: (http://localhost:8080/server-1.3.11-SNAPSHOT/webstart/xalan.jar, 2.7.1)
    at com.sun.deploy.cache.CacheEntry.writeManifest(Unknown Source)
    at com.sun.deploy.cache.CacheEntry.access$2000(Unknown Source)
    at com.sun.deploy.cache.CacheEntry$9.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.deploy.cache.CacheEntry.writeFileToDisk(Unknown Source)
    at com.sun.deploy.cache.Cache.downloadResourceToTempFile(Unknown Source)
    at com.sun.deploy.cache.Cache.downloadResourceToCache(Unknown Source)
    at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source)
    at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
    at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
    at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
    at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
    at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
    at com.sun.javaws.LaunchDownload$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)

Under Linux und Mac it runs perfectly.

I also signed and verified the xalan.jar manually over the jarsigner.exe. Output开发者_JS百科: "jar verified"

What can be the problem?