🚀 go-pugleaf

Hello, i have a simple example but when i execute it, nothing prints. Can
anyone explain , why;

import java.io.*;
import javax.print.*;
import javax.print.attribute.*;
import javax.print.attribute.standard.*;
...........

DocFlavor flavor = DocFlavor.INPUT_STREAM.TEXT_PLAIN_HOST;
    PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet();
    aset.add(MediaSizeName.ISO_A4);
    aset.add(new Copies(1));
    PrintService[] pservices =
PrintServiceLookup.lookupPrintServices(flavor, aset);
//  the pservices.length is 0. why?
// the printers that i have are:
// EPSON STYLUS COLOR 900
// HP LASERJET 6P
// OFFICEJET 6100 SERIES
    if (pservices.length > 0) {
      System.out.println("selected printer " + pservices[0].getName());
      DocPrintJob pj = pservices[0].createPrintJob();
      try {
// test.txt is a simple text/plain file
        FileInputStream fis = new FileInputStrea("c://tmp//test.txt");
        Doc doc = new SimpleDoc(fis, flavor, null);
        pj.print(doc, aset);
      }
      catch (IOException ie) {
        System.err.println(ie);
      }
      catch (PrintException e) {
        System.err.println(e);
      }

Is it possible none of these printers to support this 'flavor'?
Did i do anything wrong?
Thanks, in advance