C# Error

Hi, Im getting following Error message, This Work flow works fine, without any problem ,but suddenly sometime this error occur. Im just wondering this is problem with our end or FTP site.

Basically programe is doing connect to remote server through the FTP and Transfering the files.

DefaultSource,Error,2,The operation has timed out. FTP Upload File {06/07/2015 11:32:46}
DefaultSource,Information,0,   at System.Net.FtpWebRequest.SyncRequestCallback(Object obj)
   at System.Net.FtpWebRequest.RequestCallback(Object obj)
   at System.Net.CommandStream.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at System.IO.Stream.Dispose()
   at System.Net.ConnectionPool.Destroy(PooledStream pooledStream)
   at System.Net.ConnectionPool.PutConnection(PooledStream pooledStream, Object owningObject, Int32 creationTimeout, Boolean canReuse)
   at System.Net.FtpWebRequest.FinishRequestStage(RequestStage stage)
   at System.Net.FtpWebRequest.GetRequestStream()
   at ROFf_IntegrationLib.IO.FTPUploadFile.Execute(CodeActivityContext context)
DefaultSource,Error,2,The workflow has been aborted. ROFf_Service.Service1.Timer1_Elapsed(Object sender, ElapsedEventArgs