getting a binding error in server program

[beginner91]

i created a client server program in MFC but when i run the server the error message "ERROR binding in the server socket" displays.
this is the first time i am using code like this so I don't know how to fix this error.

here is the code:

void CSocketTestServerDlg::StartServer()
{
    WORD w = MAKEWORD(1,1);
    WSADATA wsadata;
    ::WSAStartup(w, &wsadata);

	char opt = 1; 
	setsockopt(m_serversocket, SOL_SOCKET, SO_BROADCAST, (char*)&opt, sizeof(char));
	SOCKADDR_IN brdcastaddr;
    int portno = 1818;

    memset(&brdcastaddr,0, sizeof(brdcastaddr));
    brdcastaddr.sin_family = AF_INET;
    brdcastaddr.sin_port = htons(portno);
    brdcastaddr.sin_addr.s_addr = INADDR_BROADCAST;

	m_serversocket = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
    if(m_serversocket == -1)
    {
        AfxMessageBox("Socket Initialiation Error");
    }

     int len = sizeof(brdcastaddr);
    char sbuf[1024];
    int ret = sendto(m_serversocket, sbuf, strlen(sbuf), 0, (sockaddr*)&brdcastaddr, len);
    if(ret < 0)
    {
         AfxMessageBox("ERROR binding in the server socket");
         exit(1);
    }

    if(listen(m_serversocket,0) < 0)
    {
         AfxMessageBox("ERROR listening in the server socket");
         exit(1);
    }	

    SetTimer(0x01, 100, NULL);
}