Database backup download using c#

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ASP.NET

Hello everyone
I am using a code written in C# for downloading backup of my sqlserver database.That code uses SMO object etc to download the backup.I am pasting my code below :

Backup backup = new Backup();
backup.Action = BackupActionType.Database;
backup.BackupSetDescription = "BackupDataBase description";
backup.BackupSetName = "megha";
backup.Database = "rukmini";
BackupDeviceItem deviceItem = new BackupDeviceItem(
                                backupDestinationFilePath,
                                DeviceType.File);
backup.Devices.Add(deviceItem);
ServerConnection connection = new ServerConnection(@"PHYZER-PCS");
connection.LoginSecure = false;
connection.Login = "sa";
connection.Password = "phyzer1234";
Server sqlServer = new Server(connection);
backup.Initialize = true;
backup.Checksum = true;
backup.ContinueAfterError = true;
backup.ExpirationDate = DateTime.Now.AddDays(3);
backup.LogTruncation = BackupTruncateLogType.Truncate;
backup.SqlBackup(sqlServer);

The above code works well for me still on local iis(i.e on my system) and also it works fine some days ago on remote server.But it has stopped working now for remote server.I don't know why.The sqlserver version is 2008.
Pls help me.