I installed the trial version "6..3.xxxxx" first and added it to my VB.Net project and everythin ran fine.
I recently bought the full version of "Ultimate FTP Componenent 6.4.60924". I uninstalled the trial version and installed the full version. I removed the project references to the trial and added the references to the full version.
I haven't changed the source code at all but now I get a compile error on the line that mentions "FileInfoCollection".