Package manager error,i read others post but i cant solve it

when i m running weka.jar (gui on windows vista)
in tools>Package Manager
it shows error...
"There was a problem establishing the package meta data cache.We'll try to use the repository directly."

java.net.UnknownHostException: weka.sourceforge.net
        at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
        at java.net.PlainSocketImpl.connect(Unknown Source)
        at java.net.SocksSocketImpl.connect(Unknown Source)
        at java.net.Socket.connect(Unknown Source)
        at sun.net.NetworkClient.doConnect(Unknown Source)
        at sun.net.www.http.HttpClient.openServer(Unknown Source)
        at sun.net.www.http.HttpClient.openServer(Unknown Source)
        at sun.net.www.http.HttpClient.<init>(Unknown Source)
        at sun.net.www.http.HttpClient.New(Unknown Source)
        at sun.net.www.http.HttpClient.New(Unknown Source)
        at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(Unknown Source)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
        at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
        at org.pentaho.packageManagement.DefaultPackageManager.getRepositoryPackageMetaDataOnlyAsZip(Unknown Source)
        at weka.core.WekaPackageManager.refreshCache(WekaPackageManager.java:821)
        at weka.core.WekaPackageManager.establishCacheIfNeeded(WekaPackageManager.java:755)
        at weka.gui.PackageManager$EstablishCache.doInBackground(PackageManager.java:285)
        at weka.gui.PackageManager$EstablishCache.doInBackground(PackageManager.java:256)
        at javax.swing.SwingWorker$1.call(Unknown Source)
        at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
        at java.util.concurrent.FutureTask.run(Unknown Source)
        at javax.swing.SwingWorker.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)

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Througth command prompt (i set my classpath for weka.jar)i used
java -Dhttp.proxyHost=slb-webcache-east.hull.ac.uk  -Dhttp.proxyPort=3128 weka.gui.GUIChooser


but also error
i want to install available time series packages(e.g.timeseriesForecasting),how can i do it through internet?

&
if above not working,tell me how to install it manually(offline) & from where should i download it