VB.NET - Checking FTP directory exists always returns true -

can tell me why function below returns true, if ftp directory in question not exist?

the value of directoryurl pass in of form:

ftp://ip_address/directory/subdirectory/

and has trailing forward slash.

public function doesdirectoryexist(directoryurl string) boolean   ' check target url formatted   if not directoryurl.startswith("ftp://") directoryurl = "ftp://" & directoryurl    ' create web request   dim request ftpwebrequest = directcast(webrequest.create(directoryurl), ftpwebrequest)   request.credentials = new networkcredential(_username, _password)   request.method = webrequestmethods.ftp.listdirectory    ' try , list contents of directory   try     using response ftpwebresponse = directcast(request.getresponse(), ftpwebresponse)       ' have been succesful directory exists       return true     end using   catch ex webexception     dim response ftpwebresponse = directcast(ex.response, ftpwebresponse)     if response.statuscode = ftpstatuscode.actionnottakenfileunavailable       return false     else       throw new applicationexception("unable determine if ftp directory exists.")     end if   end try end function 

weird. works me (i don't cast request guess shouldn't matter). code rely on:

dim response ftpwebresponse = request.getresponse() using (response)     found = true end using 

the alternative have reading list of directories:

using sr new system.io.streamreader(response.getresponsestream())     using sw new system.io.streamwriter("tempfile", false)         sw.write(sr.readtoend())     end using end using 

in worst scenario, should tackle problem (e.g., founds directory called "ghost", might use trigger not-found).