An exception occurred while downloading the manifest. The remote server returned an error: (407) Proxy Authentication Required. When run xbap file.

I've developed WPF Browser application and published it to the live hosting server after well testing.
My client has configured proxy server for internet use for each system. When my client is visitng the wpf site, xbap file is getting downloaded but it's manifest file isn't.
And they are getting below mentioned error. But when they visit the same url without proxy server, the site is working fine.

Please give me the solution.
The error is :
ERROR DETAILS
    Following errors were detected during this operation.
    * [4/12/2013 3:47:07 PM] System.Deployment.Application.DeploymentDownloadException (Unknown subtype)
        - Downloading http://agpweb.axiscrm.in/WPF Publish/Authorization/AGPWebWPF.xbap did not succeed.
        - Source: System.Deployment
        - Stack trace:
            at System.Deployment.Application.SystemNetDownloader.DownloadSingleFile(DownloadQueueItem next)
            at System.Deployment.Application.SystemNetDownloader.DownloadAllFiles()
            at System.Deployment.Application.FileDownloader.Download(SubscriptionState subState)
            at System.Deployment.Application.DownloadManager.DownloadManifestAsRawFile(Uri& sourceUri, String targetPath, IDownloadNotification notification, DownloadOptions options, ServerInformation& serverInformation)
            at System.Deployment.Application.DownloadManager.DownloadDeploymentManifestDirect(SubscriptionStore subStore, Uri& sourceUri, TempFile& tempFile, IDownloadNotification notification, DownloadOptions options, ServerInformation& serverInformation)
            at System.Deployment.Application.DownloadManager.DownloadDeploymentManifest(SubscriptionStore subStore, Uri& sourceUri, TempFile& tempFile, IDownloadNotification notification, DownloadOptions options)
            at System.Deployment.Application.DeploymentManager.BindCore(Boolean blocking, TempFile& tempDeploy, TempDirectory& tempAppDir, FileStream& refTransaction, String& productName)
            at System.Deployment.Application.DeploymentManager.BindAsyncWorker()
        --- Inner Exception ---
        System.Net.WebException
        - The remote server returned an error: (407) Proxy Authentication Required.
        - Source: System
        - Stack trace:
            at System.Net.HttpWebRequest.GetResponse()
            at System.Deployment.Application.SystemNetDownloader.DownloadSingleFile(DownloadQueueItem next)