Why _FileListToArray('NAS DIRECTORY','*.rtf') -- returns 4

;EXAMPLE #1
$f_directory = 'c:\1\' ; local hard drive
$a_files = _FileListToArray($f_directory, "*.rtf", 1)
ConsoleWrite('@error = ' & @error & @CRLF) ; returns 0

;EXAMPLE #2
$f_directory = 'K:\1\' ; NetworkAreaStorage
$a_files = _FileListToArray($f_directory, "*.rtf", 1)
ConsoleWrite('@error = ' & @error & @CRLF) ; returns 4

;EXAMPLE #3
$f_directory = 'K:\1\' ; NetworkAreaStorage
$a_files = _FileListToArray($f_directory, "*rtf", 1)
ConsoleWrite('@error = ' & @error & @CRLF) ; returns 0