I have found theat the CoreFTP client v2.2 can be used to send files to a CompleteFTP server however the following error message is generated
2012-10-21 11:15:08,722 INFO FTP.StoreCommand [1:ServiceNet] Upload of file /ftproot/ServiceNet/Nokia_C2-01_UG_en.pdf completed
2012-10-21 11:15:08,738 INFO TRI.Audit Default Site 94.174.206.194 ServiceNet UploadFile /ftproot/ServiceNet/Nokia_C2-01_UG_en.pdf
2012-10-21 11:15:08,832 ERROR FTP.MTDMCommand [1:ServiceNet] failed to find modified-time: 20120924211722 Nokia_C2-01_UG_en.pdf
EnterpriseDT.Net.FtpServer.FileSystem.VirtualNotFoundException: 20120924211722 Nokia_C2-01_UG_en.pdf
at EnterpriseDT.Net.FtpServer.FileSystem.Windows.WindowsAdapter.assgNnOgRI(ISession , IFileSystemNode , String )
at EnterpriseDT.Net.FtpServer.FileSystem.Windows.WindowsAdapter.GetModifiedTime(ISession session, IFileSystemNode node, String path)
at Xnc6oOOUYC1HmtZRB2f.WuccqMO958Zmo6uBn9l.D5vfwdt8l3(ISession )
at M6fh6srjRJ2isVg2HIB.lhJ6MSrTkIvWACnvuH9.Process(OBEEM20zc2WqwyQjUHo , String , String )
It looks like CoreFTP is not correctly seting the modified file time.
This does not appear to be a problem with other clients I have used with this server.