LINK : fatal error LNK1181: cannot open input file 'C:\upp\out\MyApps\Web\MSC9.Force_Size.Gui.Mt\Web.lib'

This is my code:
#ifndef _ConnSock_ConnSock_h_
#define _ConnSock_ConnSock_h_

#include <Core/Core.h>

using namespace Upp;

bool IO;
String snd(String r, int a){
	TcpSocket s;
	if(!s.Connect("127.0.0.1", 11811)) {
	    return "x";
	}

	if(IO) s.Put(r + "\n\0");
	if(a==1 && IO){
    	String st = s.GetLine();
	    return st;
	}
	return "y";
}
#endif