Can't open files on FTP server from user control

In my ASP website, I've have logic to pull back a list of files from an FTP site folder, then when the user selects one and presses a button it will open the file using this logic: 


            daDate = dtpDate.SelectedDate
            sFile = lstFiles.SelectedValue
            sPath = sPath & Format(daDate, "yyyy/MM/dd") & "/"
            Dim sFilePath As String = "ftp://" & sUser & ":" & sPass & "@" & sHost & "/" & sPath & sFile

            Response.Write("<script language = ""Javascript"">var win=window.open('" + ...