While updating the studio i got this error

why i'm unable to update my studio and sdk... below is the error i'm getting. can anybody help me out??? Thanks

SUBENTRY 3 com.aptana.core.epl 4 0 2013-07-24 17:06:08.497
!MESSAGE java.net.UnknownHostException: api.appcelerator.net
!STACK 0
java.net.UnknownHostException: api.appcelerator.net
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at org.eclipse.ecf.provider.filetransfer.events.socket.SocketEventCreateUtil.createSocket(SocketEventCreateUtil.java:43)
    at org.eclipse.ecf.internal.provider.filetransfer.httpclient.ECFHttpClientProtocolSocketFactory.createSocket(ECFHttpClientProtocolSocketFactory.java:81)
    at org.eclipse.ecf.internal.provider.filetransfer.httpclient.ECFHttpClientProtocolSocketFactory.createSocket(ECFHttpClientProtocolSocketFactory.java:73)
    at org.eclipse.ecf.internal.provider.filetransfer.httpclient.ECFHttpClientProtocolSocketFactory.createSocket(ECFHttpClientProtocolSocketFactory.java:65)
    at org.apache.commons.httpclient.HttpConnection.open(HttpConnection.java:707)
    at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$HttpConnectionAdapter.open(MultiThreadedHttpConnectionManager.java:1361)
    at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:387)
    at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171)
    at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
    at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:346)
    at org.eclipse.ecf.provider.filetransfer.httpclient.HttpClientRetrieveFileTransfer.performConnect(HttpClientRetrieveFileTransfer.java:1142)
    at org.eclipse.ecf.provider.filetransfer.httpclient.HttpClientRetrieveFileTransfer.openStreams(HttpClientRetrieveFileTransfer.java:710)
    at org.eclipse.ecf.provider.filetransfer.retrieve.AbstractRetrieveFileTransfer.sendRetrieveRequest(AbstractRetrieveFileTransfer.java:889)
    at org.eclipse.ecf.provider.filetransfer.retrieve.MultiProtocolRetrieveAdapter.sendRetrieveRequest(MultiProtocolRetrieveAdapter.java:146)
    at com.aptana.core.epl.downloader.FileReader.sendRetrieveRequest(FileReader.java:442)
    at com.aptana.core.epl.downloader.FileReader.readInto(FileReader.java:377)
    at com.aptana.ide.core.io.downloader.ContentDownloadRequest.download(ContentDownloadRequest.java:104)
    at com.aptana.ide.core.io.downloader.ContentDownloadRequest.execute(ContentDownloadRequest.java:81)
    at com.aptana.ide.core.io.downloader.DownloadManager.download(DownloadManager.java:138)
    at com.aptana.ide.core.io.downloader.DownloadManager.start(DownloadManager.java:118)
    at com.appcelerator.titanium.update.TitaniumUpdaterUtil.installSDKs(TitaniumUpdaterUtil.java:144)
    at com.appcelerator.titanium.update.internal.TitaniumSDKRelease.install(TitaniumSDKRelease.java:130)
    at com.appcelerator.titanium.update.TitaniumSDKUpdater.installTitaniumUpdates(TitaniumSDKUpdater.java:482)
    at com.appcelerator.titanium.update.TitaniumSDKUpdater.access$0(TitaniumSDKUpdater.java:447)
    at com.appcelerator.titanium.update.TitaniumSDKUpdater$5.run(TitaniumSDKUpdater.java:870)
    at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)