Flex. PrintJob - pageWidth pageHeight bad values

Question

Hello :)

I have:

var pj:PrintJob = new PrintJob();
if (pj.start())
{
  trace(pj.pageWidth);
  trace(pj.pageHeight);
  (...)
}

Problem: low/bad values pageWidth and pageHeight. For printer 600dpi: pj.pageWidth=595 and pj.pageHeight=842 for A4 page !

How can I increase DPI printed page?

Please help