Linker error

  [Linker error] undefined reference to `ChebTCPServerSocket::ServerSocket' 
 C:\Users\Ìèõàèë\Desktop\SCheb21\main.o(.text+0x156) In function `ZN19ChebTCPServerSocket12ClientAcceptEPv': 
 C:\Users\Ìèõàèë\Desktop\SCheb21\cheb21.o(.text+0x0) In function `ZN19ChebTCPServerSocket11StartServerEv': 
51 C:\Users\Ìèõàèë\Desktop\SCheb21\ChebTCP.h multiple definition of `ChebTCPServerSocket::StartServer()' 
95 C:\Users\Ìèõàèë\Desktop\SCheb21\ChebTCP.h multiple definition of `_ZN19ChebTCPServerSocket12ClientThreadEPv@4'

#include <windows.h>
#include <iostream>
#include <conio.h>
#include <stdlib.h>
#include <winsock2.h>
//#include "cheb21.h"
#pragma once
#define BUFFSIZE 4096
#define MAXCONNECTION 500
using namespace std;
//------------------------------------------------------------------------------
struct UserOnline{
    bool registred;
    char IP[16];
    int ID;
    int IDOnline;
    SOCKET UserSocket;
    int SendText(char buff[BUFFSIZE]);
};
//------------------------------------------------------------------------------
class ChebTCPServerSocket{
public:
    short int PORT;
    int MAXCONNECTIONS;
    static int COUNT;
    //Functions
    int StartServer();
    int StopServer();
    static UserOnline *User;
private:
    static  bool ServerActive;
    static SOCKET ServerSocket;
    static SOCKET TempSocket;
    static DWORD WINAPI ClientAccept(LPVOID Nothing);
    static DWORD WINAPI ClientThread(LPVOID User);
};
//------------------------------------------------------------------------------
int ChebTCPServerSocket::StartServer()
{
    if(PORT==0){return -1;}
    WSADATA *WsaData;
    if(WSAStartup(0x202,WsaData))
    ServerSocket=socket(AF_INET,SOCK_STREAM,0);
    if(ServerSocket==INVALID_SOCKET){return -2;}
    sockaddr_in ServerAddr;
    ServerAddr.sin_family=AF_INET;
    ServerAddr.sin_port=htons(PORT);
    ServerAddr.sin_addr.s_addr=0;
    if(bind(ServerSocket,(sockaddr *)&ServerAddr,sizeof(ServerAddr))!=0)
    {return -3;}
    if(listen(ServerSocket,0x100))
    {return -4;}
    ServerActive=true;
    CreateThread(0,0,&ClientAccept,0,0,0);
    return 0;
}
//------------------------------------------------------------------------------
DWORD WINAPI ChebTCPServerSocket::ClientAccept(LPVOID Nothing)
{
    sockaddr ClientAddr;
    int ClientAddrSize=sizeof(ClientAddr);
    int Id;
    while((TempSocket=accept(ServerSocket,&ClientAddr,&ClientAddrSize))&&ServerActive==true)
    {
        COUNT++;
        User=new UserOnline;
        HOSTENT *hst;
        hst=gethostbyname((char*)&ClientAddr);
 
        for(Id=0;Id<sizeof(User);Id++)
        {
            if(User[Id].ID==0&&User[Id].IDOnline==0&&User[Id].IP=="")
            {
                strcat(User[Id].IP,(char*)&ClientAddr);
                User[Id].IDOnline=Id;
                break;
            }
        }
    CreateThread(0,0,&ClientThread,&User[Id],0,0);
    }
}
//------------------------------------------------------------------------------
    DWORD WINAPI ChebTCPServerSocket::ClientThread(LPVOID User)
    {
        UserOnline *Usermem;
        Usermem=(UserOnline *)User;
        char buff[BUFFSIZE];
        while(int SizeRecv=recv(Usermem->UserSocket,buff,BUFFSIZE,0)&&SizeRecv==INVALID_SOCKET)
        {}
        delete Usermem;
    }
//------------------------------------------------------------------------------

  [Linker error] undefined reference to `ChebTCPServerSocket::StopServer()'

int ChebTCPServerSocket::StartServer()
{
    if(PORT==0){return -1;}
    WSADATA *WsaData;
    if(WSAStartup(0x202,WsaData))
    ServerSocket=socket(AF_INET,SOCK_STREAM,0);
    if(ServerSocket==INVALID_SOCKET){return -2;}
    sockaddr_in ServerAddr;
    ServerAddr.sin_family=AF_INET;
    ServerAddr.sin_port=htons(PORT);
    ServerAddr.sin_addr.s_addr=0;
    if(bind(ServerSocket,(sockaddr *)&ServerAddr,sizeof(ServerAddr))!=0)
    {return -3;}
    if(listen(ServerSocket,0x100))
    {return -4;}
    ServerActive=true;
    CreateThread(0,0,&ClientAccept,0,0,0);
    return 0;
}

WSADATA WsaData;
if(WSAStartup(0x202,&WsaData))
    ...

//in Cheb21.h
class Cheb21 {
       public:
       ChebTCPServerSocket *ServerSocket;
       };
//In main()
Cheb21 *cheb21;
cheb21->ServerSocket->StartServer();