macromedia flash flash remoting:

I believe my action script code is ok because it's working fine locally.
here it is :
#include "NetServices.as"
#include "NetDebug.as"
var gateconn;
var serviceconn;
mx.remoting.debug.NetDebug.initialize()
NetServices.setDefaultGatewayUrl("http://www.mydomain.com/gateway.aspx");
gateconn = NetServices.createGatewayConnection();
serviceconn = gateconn.getService("dll_name", this);
serviceconn.class_name;
function au_login_Result(Results) {
text_txt.text = Results;
}
function au_login_Status(Status) {
text_txt.text = Status;
}

I'm using : visual studio 2003, IIS 5.1, net.framework 1.1

is it possible to be a web server security issue???