Try enabling ForceListHiddenFiles option before calling GetList, GetRawList or GetNameList method.
C#:
Ftp client = new Ftp();
client.Options |= FtpOptions.ForceListHiddenFiles;
...
VB.NET:
Dim client As New Ftp()
client.Options = client.Options Or FtpOptions.ForceListHiddenFiles
...