Poco compression giving a negative ratio

I tried creating the .gz file using poco functions but gives the negative ratio when given to gzip

gzip -l simple.gzip compressed uncompressed ratio uncompressed_name 106 42 -90.5% simple.gzip

#include <stdexcept>
#include <stdarg.h>
#include <map>
#include <iostream>
 #include <cstring>
#include <fstream>
 #include <Poco/DeflatingStream.h>
 #include <stdio.h>
#include <limits>
#include <stdio.h>
#include <unistd.h>
using namespace std;

int main(){

std::ofstream* ostr;
Poco::DeflatingOutputStream* ofstr;
string fileName="/home/lamb/Cpp/simple.gzip";
ostr = new std::ofstream;
ostr->exceptions(std::ofstream::failbit|std::ofstream::badbit);
ostr->open(_fileName.c_str(), std::ios::binary | std::ios::app);
ofstr = new Poco::DeflatingOutputStream(*_ostr,         
Poco::DeflatingStreamBuf::STREAM_GZIP);
ofstr->precision(std::numeric_limits<double>::digits10);



*ofstr << "\t<xyz>\n";
*ofstr << "\t</xyz>\n";
*ofstr << " who=\"";
      *ofstr << "/>\n";

      ofstr->close();
      delete ofstr;
      ofstr = NULL;
      ostr->close();
      delete ostr;
      ostr = NULL;

      ostr = new std::ofstream;
      ostr->exceptions(std::ofstream::failbit|std::ofstream::badbit);
      ostr->open(fileName.c_str(), std::ios::binary | std::ios::app);
      ofstr = new Poco::DeflatingOutputStream(*ostr,     
     Poco::DeflatingStreamBuf::STREAM_GZIP);
      ofstr->precision(std::numeric_limits<double>::digits10);

      *ofstr << "\t<xyz>\n";
      *ofstr << "\t</xyz>\n";
      *ofstr << " hello=\"";
            *ofstr << "/>\n";


    ofstr->close();
   ostr->close();

    delete ofstr;
    delete ostr;

    }