server client file transfer problem

Dear Experts,

Greetings, This is my program:
This program is a server-client file transfer program.

The client will send the file localtion (full path of the document at server)
to the server.
Server will zip the file (external program,PKzip) and send the zipped file size to client to prepare the buffer.
After Zipped, the server will open the zipped file in binary and send to client.

The problem i facing is:
the client can receive the 1st request file (less than 10KB)
but when the 2nd file (> 20MB)
the client receive failed.

when I change the 2nd file size to less than 10KB,
it's work.

below is the coding:
=============

//*********************************************//
//    client's getFile functiion
//*********************************************//
bool GetFile(SOCKET theClient, char file[256], int &theSize)
{
      int iRet;
      FILE *fout;
      char fileName[256];
      CClientDlg Dlg;
      char counter[128];
      int TotalBytes = 0;

        strcpy(fileName, file);


      iRet = send(theClient, fileName, sizeof(fileName), 0);

      if (iRet == SOCKET_ERROR)
      {
        int err = WSAGetLastError();
            Dlg.MessageBox((char *)err,0,0);//TEXT("Error at send begin %d",err), 0, 0);

            return false;
      }

      //get the file size
      iRet = recv(theClient, counter, sizeof(counter), 0);
   
    if (iRet == SOCKET_ERROR)
    {
        return false;
    }

/*
// i try to wait until to get the file size
     while (iRet != atoi(counter))
    {
          iRet = recv(theClient, counter, sizeof(counter), 0);

        if (iRet == SOCKET_ERROR)
          {
            return false;
          }
    };*/
      
      int FileSize = atoi(counter);
      if (FileSize == 0)
            return false;

      theSize = FileSize;

      char RootDir[MAX_PATH];
      strcpy(RootDir, fileName);
      DirStrip(RootDir, fileName);

      char *buffer = new char[FileSize];
      int b_receive;
      iRet = 0;
      for (int i = 0; i < FileSize; i += iRet)
      {
            b_receive = FileSize - TotalBytes;
            iRet = recv(theClient, &buffer[i], b_receive, 0);
            TotalBytes += iRet;
            if (iRet == SOCKET_ERROR)
            {
                  int a = WSAGetLastError();
            closesocket(theClient);
                  Dlg.MessageBox("error error", 0, 0);

                  return false;
            }
      }


      //this gets the total bytes sent from server to check if file was recv correct
      char total[12];

      itoa(TotalBytes, total, 10);
      recv(theClient, total, sizeof(total), 0);
      
    if (atoi(total) != TotalBytes)
    {
            return false;
    }

    char *tempIndex = new char [3];

    strcpy(fileName, "c:\\temp\\WVS");
    strcat(fileName, itoa(downloadIndex,tempIndex,10));
    strcat(fileName, ".zip");

    strcpy(fileDownload[downloadIndex].zipFileName, fileName);
    downloadIndex++;

    delete[] tempIndex;

    if( (fout = fopen(fileName, "wb")) != NULL)
    {
          fwrite(buffer, FileSize,1,fout);
              fclose(fout);


    }

      delete[] buffer;

      closesocket(theClient);

    return true;
}

//*********************************************//
//   server's sendFile functiion
//*********************************************//
bool SendFile(SOCKET sock)
{
      char fileName[256];
      char TempZip[256];
      FILE *fin;
      int iRet;
      int counter = 0;
      int TotalBytes = 0;
      char *tempChar = new char [12];

      memset(fileName, 0, sizeof(fileName));
      
      iRet = recv(sock, fileName, sizeof(fileName), 0);
      if (iRet == SOCKET_ERROR)
            MessageBox(NULL, "Error receiving filename", 0, 0);


      strcpy(TempZip, "C:\\Temp\\");
      strcat(TempZip, itoa(fileCounter, tempChar, 10));
      strcat(TempZip, ".zip ");

      strcpy(tempChar, TempZip);

      strcat(TempZip,fileName);

      fileCounter++;
      
      
      HINSTANCE hInst = ShellExecute(0,
    "open", // Operation to perform
    "c:\\PKzip_Utility\\pkzip.exe", // Application name
    (LPCTSTR)TempZip,
      NULL, // Default directory
      SW_HIDE); // Hide the zip screen
      
      
     strcpy(fileName, tempChar);

      while((fin = fopen(fileName,"rb")) == NULL); // if the zip file not exist yet then become NULL

      counter = filesize(fin);
      char FileSize[128];
      itoa(counter, FileSize, 10);
      

      iRet = send(sock, FileSize, sizeof(FileSize), 0);
      if (iRet == SOCKET_ERROR)
      {
            return false;
      }

      char *ToSend = new char[counter];
      fseek(fin, 0, SEEK_SET);      //move to begining of file again

      fread(ToSend, counter,1,fin);

      iRet = send(sock, ToSend, counter, 0);
      
      TotalBytes += iRet;
      if (iRet == SOCKET_ERROR)
      {
                  fclose(fin);
                  closesocket(sock);
            int error=WSAGetLastError();
            if (error==WSAEMSGSIZE)
            return false;
      }
            
      //send the actual bytes sent
      char total[12];
      itoa(TotalBytes, total, 10);
      send(sock, total, sizeof(total), 0);

      //file transfer is complete, so close the socket and file stream
      delete [] ToSend;

      fclose(fin);
      closesocket(sock);

      return true;
}


Thanks.


regards,
Kgc