Help TCPListen

TCPStartup()
Global $Server
Global $sIPAddress = TCPNameToIP('some.no-ip.info')
Global $nPort = 80
$Server = TCPListen($sIPAddress,$nPort)

IF @error Then
MsgBox('','','Error')
Exit
EndIf


Hi Dudes , a litle  question , hope they can  help me  :

Why i Get error  on try  to connect  an external IP using No-Ip  , and if I put  No-IP to localhost , yes its work good
...  What Happening ?  thanks  for all and  sorry  , regards